diff --git a/backend/Cargo.lock b/backend/Cargo.lock
index 1c503c2..b9586a0 100644
--- a/backend/Cargo.lock
+++ b/backend/Cargo.lock
@@ -428,6 +428,7 @@ dependencies = [
  "log",
  "openidconnect",
  "serde",
+ "sqlx",
 ]
 
 [[package]]
diff --git a/backend/feature/auth/Cargo.toml b/backend/feature/auth/Cargo.toml
index 26ffa18..27362a0 100644
--- a/backend/feature/auth/Cargo.toml
+++ b/backend/feature/auth/Cargo.toml
@@ -10,3 +10,4 @@ async-trait.workspace = true
 log.workspace = true
 openidconnect.workspace = true
 serde.workspace = true
+sqlx.workspace = true
diff --git a/backend/feature/auth/src/adapter/delivery/user_response_dto.rs b/backend/feature/auth/src/adapter/delivery/user_response_dto.rs
index 975ab8c..2726c57 100644
--- a/backend/feature/auth/src/adapter/delivery/user_response_dto.rs
+++ b/backend/feature/auth/src/adapter/delivery/user_response_dto.rs
@@ -4,7 +4,7 @@ use crate::domain::entity::user::User;
 
 #[derive(Serialize)]
 pub struct UserResponseDto {
-    pub source_id: String,
+    pub id: i32,
     pub displayed_name: String,
     pub email: String,
 }
@@ -12,7 +12,7 @@ pub struct UserResponseDto {
 impl From<User> for UserResponseDto {
     fn from(user: User) -> Self {
         UserResponseDto {
-            source_id: user.source_id,
+            id: user.id,
             displayed_name: user.displayed_name,
             email: user.email,
         }
diff --git a/backend/feature/auth/src/adapter/gateway.rs b/backend/feature/auth/src/adapter/gateway.rs
index d813de5..9a26c24 100644
--- a/backend/feature/auth/src/adapter/gateway.rs
+++ b/backend/feature/auth/src/adapter/gateway.rs
@@ -1,3 +1,5 @@
-pub mod oidc_claims_response_dto;
 pub mod auth_oidc_service;
 pub mod auth_repository_impl;
+pub mod oidc_claims_response_dto;
+pub mod user_db_service;
+pub mod user_mapper;
diff --git a/backend/feature/auth/src/adapter/gateway/auth_repository_impl.rs b/backend/feature/auth/src/adapter/gateway/auth_repository_impl.rs
index 533da3a..c480ae9 100644
--- a/backend/feature/auth/src/adapter/gateway/auth_repository_impl.rs
+++ b/backend/feature/auth/src/adapter/gateway/auth_repository_impl.rs
@@ -3,7 +3,9 @@ use std::sync::Arc;
 use async_trait::async_trait;
 
 use crate::{
-    adapter::gateway::auth_oidc_service::AuthOidcService,
+    adapter::gateway::{
+        auth_oidc_service::AuthOidcService, user_db_service::UserDbService, user_mapper::UserMapper,
+    },
     application::{
         error::auth_error::AuthError, gateway::auth_repository::AuthRepository,
         use_case::get_auth_url_use_case::AuthUrl,
@@ -12,12 +14,19 @@ use crate::{
 };
 
 pub struct AuthRepositoryImpl {
+    user_db_service: Arc<dyn UserDbService>,
     auth_oidc_service: Arc<dyn AuthOidcService>,
 }
 
 impl AuthRepositoryImpl {
-    pub fn new(auth_oidc_service: Arc<dyn AuthOidcService>) -> Self {
-        Self { auth_oidc_service }
+    pub fn new(
+        user_db_service: Arc<dyn UserDbService>,
+        auth_oidc_service: Arc<dyn AuthOidcService>,
+    ) -> Self {
+        Self {
+            user_db_service,
+            auth_oidc_service,
+        }
     }
 }
 
@@ -37,4 +46,21 @@ impl AuthRepository for AuthRepositoryImpl {
             .await
             .map(|dto| dto.into_entity())
     }
+
+    async fn get_user_by_source_id(
+        &self,
+        issuer: &str,
+        source_id: &str,
+    ) -> Result<User, AuthError> {
+        self.user_db_service
+            .get_user_by_source_id(issuer, source_id)
+            .await
+            .map(|mapper| mapper.into_entity())
+    }
+
+    async fn save_user(&self, user: User) -> Result<i32, AuthError> {
+        self.user_db_service
+            .create_user(UserMapper::from(user))
+            .await
+    }
 }
diff --git a/backend/feature/auth/src/adapter/gateway/oidc_claims_response_dto.rs b/backend/feature/auth/src/adapter/gateway/oidc_claims_response_dto.rs
index 94c17b7..3d36876 100644
--- a/backend/feature/auth/src/adapter/gateway/oidc_claims_response_dto.rs
+++ b/backend/feature/auth/src/adapter/gateway/oidc_claims_response_dto.rs
@@ -2,6 +2,7 @@ use crate::domain::entity::user::User;
 
 pub struct OidcClaimsResponseDto {
     pub sub: String,
+    pub issuer: String,
     pub preferred_username: Option<String>,
     pub email: Option<String>,
 }
@@ -9,6 +10,8 @@ pub struct OidcClaimsResponseDto {
 impl OidcClaimsResponseDto {
     pub fn into_entity(self) -> User {
         User {
+            id: -1,
+            issuer: self.issuer,
             source_id: self.sub,
             displayed_name: self.preferred_username.unwrap_or_default(),
             email: self.email.unwrap_or_default(),
diff --git a/backend/feature/auth/src/adapter/gateway/user_db_service.rs b/backend/feature/auth/src/adapter/gateway/user_db_service.rs
new file mode 100644
index 0000000..93eff18
--- /dev/null
+++ b/backend/feature/auth/src/adapter/gateway/user_db_service.rs
@@ -0,0 +1,14 @@
+use async_trait::async_trait;
+
+use crate::{adapter::gateway::user_mapper::UserMapper, application::error::auth_error::AuthError};
+
+#[async_trait]
+pub trait UserDbService: Send + Sync {
+    async fn get_user_by_source_id(
+        &self,
+        issuer: &str,
+        source_id: &str,
+    ) -> Result<UserMapper, AuthError>;
+
+    async fn create_user(&self, user: UserMapper) -> Result<i32, AuthError>;
+}
diff --git a/backend/feature/auth/src/adapter/gateway/user_mapper.rs b/backend/feature/auth/src/adapter/gateway/user_mapper.rs
new file mode 100644
index 0000000..31a01d0
--- /dev/null
+++ b/backend/feature/auth/src/adapter/gateway/user_mapper.rs
@@ -0,0 +1,33 @@
+use crate::domain::entity::user::User;
+
+pub struct UserMapper {
+    pub id: i32,
+    pub issuer: String,
+    pub source_id: String,
+    pub displayed_name: String,
+    pub email: String,
+}
+
+impl From<User> for UserMapper {
+    fn from(user: User) -> Self {
+        Self {
+            id: user.id,
+            issuer: user.issuer,
+            source_id: user.source_id,
+            displayed_name: user.displayed_name,
+            email: user.email,
+        }
+    }
+}
+
+impl UserMapper {
+    pub fn into_entity(self) -> User {
+        User {
+            id: self.id,
+            issuer: self.issuer,
+            source_id: self.source_id,
+            displayed_name: self.displayed_name,
+            email: self.email,
+        }
+    }
+}
diff --git a/backend/feature/auth/src/application/error/auth_error.rs b/backend/feature/auth/src/application/error/auth_error.rs
index 820a405..9fa2375 100644
--- a/backend/feature/auth/src/application/error/auth_error.rs
+++ b/backend/feature/auth/src/application/error/auth_error.rs
@@ -1,8 +1,10 @@
 #[derive(Debug, PartialEq)]
 pub enum AuthError {
+    DatabaseError(String),
     OidcError(String),
     InvalidState,
     InvalidNonce,
     InvalidAuthCode,
     InvalidIdToken,
+    UserNotFound,
 }
diff --git a/backend/feature/auth/src/application/gateway/auth_repository.rs b/backend/feature/auth/src/application/gateway/auth_repository.rs
index 98a12f5..c88567c 100644
--- a/backend/feature/auth/src/application/gateway/auth_repository.rs
+++ b/backend/feature/auth/src/application/gateway/auth_repository.rs
@@ -8,6 +8,12 @@ use crate::{
 #[async_trait]
 pub trait AuthRepository: Send + Sync {
     fn get_auth_url(&self) -> Result<AuthUrl, AuthError>;
+
     async fn exchange_auth_code(&self, code: &str, expected_nonce: &str)
     -> Result<User, AuthError>;
+
+    async fn get_user_by_source_id(&self, issuer: &str, source_id: &str)
+    -> Result<User, AuthError>;
+
+    async fn save_user(&self, user: User) -> Result<i32, AuthError>;
 }
diff --git a/backend/feature/auth/src/application/use_case/exchange_auth_code_use_case.rs b/backend/feature/auth/src/application/use_case/exchange_auth_code_use_case.rs
index 65e90d1..90990e6 100644
--- a/backend/feature/auth/src/application/use_case/exchange_auth_code_use_case.rs
+++ b/backend/feature/auth/src/application/use_case/exchange_auth_code_use_case.rs
@@ -41,8 +41,24 @@ impl ExchangeAuthCodeUseCase for ExchangeAuthCodeUseCaseImpl {
             return Err(AuthError::InvalidState);
         }
 
-        self.auth_repository
+        let mut logged_in_user = self
+            .auth_repository
             .exchange_auth_code(code, expected_nonce)
-            .await
+            .await?;
+
+        let saved_user = self
+            .auth_repository
+            .get_user_by_source_id(&logged_in_user.issuer, &logged_in_user.source_id)
+            .await;
+
+        if saved_user.err() == Some(AuthError::UserNotFound) {
+            let id = self
+                .auth_repository
+                .save_user(logged_in_user.clone())
+                .await?;
+            logged_in_user.id = id;
+        }
+
+        Ok(logged_in_user)
     }
 }
diff --git a/backend/feature/auth/src/domain/entity/user.rs b/backend/feature/auth/src/domain/entity/user.rs
index 2cd83ca..a03bc1e 100644
--- a/backend/feature/auth/src/domain/entity/user.rs
+++ b/backend/feature/auth/src/domain/entity/user.rs
@@ -1,4 +1,7 @@
+#[derive(Clone)]
 pub struct User {
+    pub id: i32,
+    pub issuer: String,
     pub source_id: String,
     pub displayed_name: String,
     pub email: String,
diff --git a/backend/feature/auth/src/framework.rs b/backend/feature/auth/src/framework.rs
index 39c6581..5dfd9bf 100644
--- a/backend/feature/auth/src/framework.rs
+++ b/backend/feature/auth/src/framework.rs
@@ -1,2 +1,3 @@
+pub mod db;
 pub mod oidc;
 pub mod web;
diff --git a/backend/feature/auth/src/framework/db.rs b/backend/feature/auth/src/framework/db.rs
new file mode 100644
index 0000000..1737d13
--- /dev/null
+++ b/backend/feature/auth/src/framework/db.rs
@@ -0,0 +1,2 @@
+pub mod user_db_service_impl;
+pub mod user_record;
diff --git a/backend/feature/auth/src/framework/db/user_db_service_impl.rs b/backend/feature/auth/src/framework/db/user_db_service_impl.rs
new file mode 100644
index 0000000..1430229
--- /dev/null
+++ b/backend/feature/auth/src/framework/db/user_db_service_impl.rs
@@ -0,0 +1,65 @@
+use async_trait::async_trait;
+use sqlx::{Pool, Postgres};
+
+use crate::{
+    adapter::gateway::{user_db_service::UserDbService, user_mapper::UserMapper},
+    application::error::auth_error::AuthError,
+    framework::db::user_record::UserRecord,
+};
+
+pub struct UserDbServiceImpl {
+    db_pool: Pool<Postgres>,
+}
+
+impl UserDbServiceImpl {
+    pub fn new(db_pool: Pool<Postgres>) -> Self {
+        Self { db_pool }
+    }
+}
+
+#[async_trait]
+impl UserDbService for UserDbServiceImpl {
+    async fn get_user_by_source_id(
+        &self,
+        issuer: &str,
+        source_id: &str,
+    ) -> Result<UserMapper, AuthError> {
+        let record = sqlx::query_as!(
+            UserRecord,
+            r#"
+            SELECT id, issuer, source_id, displayed_name, email
+            FROM "user"
+            WHERE issuer = $1 AND source_id = $2
+            "#,
+            issuer,
+            source_id
+        )
+        .fetch_optional(&self.db_pool)
+        .await
+        .map_err(|e| AuthError::DatabaseError(e.to_string()))?;
+
+        match record {
+            Some(record) => Ok(record.into_mapper()),
+            None => Err(AuthError::UserNotFound),
+        }
+    }
+
+    async fn create_user(&self, user: UserMapper) -> Result<i32, AuthError> {
+        let id = sqlx::query_scalar!(
+            r#"
+            INSERT INTO "user" (issuer, source_id, displayed_name, email)
+            VALUES ($1, $2, $3, $4)
+            RETURNING id
+            "#,
+            user.issuer,
+            user.source_id,
+            user.displayed_name,
+            user.email
+        )
+        .fetch_one(&self.db_pool)
+        .await
+        .map_err(|e| AuthError::DatabaseError(e.to_string()))?;
+
+        Ok(id)
+    }
+}
diff --git a/backend/feature/auth/src/framework/db/user_record.rs b/backend/feature/auth/src/framework/db/user_record.rs
new file mode 100644
index 0000000..7f296d8
--- /dev/null
+++ b/backend/feature/auth/src/framework/db/user_record.rs
@@ -0,0 +1,24 @@
+use sqlx::FromRow;
+
+use crate::adapter::gateway::user_mapper::UserMapper;
+
+#[derive(FromRow)]
+pub struct UserRecord {
+    pub id: i32,
+    pub issuer: String,
+    pub source_id: String,
+    pub displayed_name: String,
+    pub email: String,
+}
+
+impl UserRecord {
+    pub fn into_mapper(self) -> UserMapper {
+        UserMapper {
+            id: self.id,
+            issuer: self.issuer,
+            source_id: self.source_id,
+            displayed_name: self.displayed_name,
+            email: self.email,
+        }
+    }
+}
diff --git a/backend/feature/auth/src/framework/oidc/auth_oidc_service_impl.rs b/backend/feature/auth/src/framework/oidc/auth_oidc_service_impl.rs
index d60f7da..d4a85dd 100644
--- a/backend/feature/auth/src/framework/oidc/auth_oidc_service_impl.rs
+++ b/backend/feature/auth/src/framework/oidc/auth_oidc_service_impl.rs
@@ -93,6 +93,8 @@ impl AuthOidcService for AuthOidcServiceImpl {
             )
             .map_err(|_| AuthError::InvalidIdToken)?;
 
+        let issuer = claims.issuer().to_string();
+
         let preferred_username = claims
             .preferred_username()
             .map(|username| username.to_string());
@@ -101,6 +103,7 @@ impl AuthOidcService for AuthOidcServiceImpl {
 
         Ok(OidcClaimsResponseDto {
             sub: claims.subject().to_string(),
+            issuer: issuer,
             preferred_username: preferred_username,
             email: email,
         })
diff --git a/backend/feature/auth/src/framework/web.rs b/backend/feature/auth/src/framework/web.rs
index 60c8eb8..8853d00 100644
--- a/backend/feature/auth/src/framework/web.rs
+++ b/backend/feature/auth/src/framework/web.rs
@@ -1 +1,3 @@
 pub mod auth_web_routes;
+
+mod constants;
diff --git a/backend/feature/auth/src/framework/web/auth_web_routes.rs b/backend/feature/auth/src/framework/web/auth_web_routes.rs
index c56dda3..f0ab70d 100644
--- a/backend/feature/auth/src/framework/web/auth_web_routes.rs
+++ b/backend/feature/auth/src/framework/web/auth_web_routes.rs
@@ -6,12 +6,11 @@ use crate::{
         auth_controller::AuthController, oidc_callback_query_dto::OidcCallbackQueryDto,
     },
     application::error::auth_error::AuthError,
+    framework::web::constants::{
+        SESSION_KEY_AUTH_NONCE, SESSION_KEY_AUTH_STATE, SESSION_KEY_USER_ID,
+    },
 };
 
-const SESSION_KEY_AUTH_STATE: &str = "auth_state";
-const SESSION_KEY_AUTH_NONCE: &str = "auth_nonce";
-const SESSION_KEY_USER: &str = "user";
-
 pub fn configure_auth_routes(cfg: &mut web::ServiceConfig) {
     cfg.service(
         web::scope("/auth")
@@ -29,11 +28,11 @@ async fn oidc_login_handler(
 
     match result {
         Ok(auth_url) => {
-            if let Err(e) = session.insert(SESSION_KEY_AUTH_STATE, auth_url.state) {
+            if let Err(e) = session.insert::<String>(SESSION_KEY_AUTH_STATE, auth_url.state) {
                 log::error!("{e:?}");
                 return HttpResponse::InternalServerError().finish();
             }
-            if let Err(e) = session.insert(SESSION_KEY_AUTH_NONCE, auth_url.nonce) {
+            if let Err(e) = session.insert::<String>(SESSION_KEY_AUTH_NONCE, auth_url.nonce) {
                 log::error!("{e:?}");
                 return HttpResponse::InternalServerError().finish();
             }
@@ -53,12 +52,12 @@ async fn oidc_callback_handler(
     query: web::Query<OidcCallbackQueryDto>,
     session: Session,
 ) -> impl Responder {
-    let expected_state: String = match session.get(SESSION_KEY_AUTH_STATE) {
+    let expected_state = match session.get::<String>(SESSION_KEY_AUTH_STATE) {
         Ok(Some(state)) => state,
         _ => return HttpResponse::BadRequest().finish(),
     };
 
-    let expected_nonce: String = match session.get(SESSION_KEY_AUTH_NONCE) {
+    let expected_nonce = match session.get::<String>(SESSION_KEY_AUTH_NONCE) {
         Ok(Some(nonce)) => nonce,
         _ => return HttpResponse::BadRequest().finish(),
     };
@@ -71,7 +70,7 @@ async fn oidc_callback_handler(
     session.remove(SESSION_KEY_AUTH_NONCE);
     match result {
         Ok(user) => {
-            if let Err(e) = session.insert(SESSION_KEY_USER, user) {
+            if let Err(e) = session.insert::<i32>(SESSION_KEY_USER_ID, user.id) {
                 log::error!("{e:?}");
                 return HttpResponse::InternalServerError().finish();
             }
@@ -95,7 +94,7 @@ async fn oidc_callback_handler(
 async fn logout_handler(session: Session) -> impl Responder {
     session.remove(SESSION_KEY_AUTH_STATE);
     session.remove(SESSION_KEY_AUTH_NONCE);
-    session.remove(SESSION_KEY_USER);
+    session.remove(SESSION_KEY_USER_ID);
     HttpResponse::Found()
         .append_header((header::LOCATION, "/"))
         .finish()
diff --git a/backend/feature/auth/src/framework/web/constants.rs b/backend/feature/auth/src/framework/web/constants.rs
new file mode 100644
index 0000000..346177d
--- /dev/null
+++ b/backend/feature/auth/src/framework/web/constants.rs
@@ -0,0 +1,3 @@
+pub const SESSION_KEY_AUTH_STATE: &str = "auth_state";
+pub const SESSION_KEY_AUTH_NONCE: &str = "auth_nonce";
+pub const SESSION_KEY_USER_ID: &str = "user_id";
diff --git a/backend/migrations/20250725231740_v0.3.0.sql b/backend/migrations/20250725231740_v0.3.0.sql
index 8186a66..4b7a6a0 100644
--- a/backend/migrations/20250725231740_v0.3.0.sql
+++ b/backend/migrations/20250725231740_v0.3.0.sql
@@ -6,7 +6,25 @@ CREATE TABLE "image" (
     "updated_time" TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
 );
 
+CREATE TABLE "user" (
+    "id" SERIAL PRIMARY KEY NOT NULL,
+    "issuer" VARCHAR(100) NOT NULL,
+    "source_id" VARCHAR(100) NOT NULL,
+    "displayed_name" VARCHAR(100) NOT NULL,
+    "email" VARCHAR(100) NOT NULL,
+    "created_time" TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updated_time" TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
+);
+
+CREATE UNIQUE INDEX "user_source_id_issuer_key" ON "user" ("source_id", "issuer");
+CREATE INDEX "user_email_key" ON "user" HASH ("email");
+
 CREATE TRIGGER "update_image_updated_time"
 BEFORE UPDATE ON "image"
 FOR EACH ROW
 EXECUTE FUNCTION update_updated_time_column();
+
+CREATE TRIGGER "update_user_updated_time"
+BEFORE UPDATE ON "user"
+FOR EACH ROW
+EXECUTE FUNCTION update_updated_time_column();
diff --git a/backend/server/src/container.rs b/backend/server/src/container.rs
index f9a04b2..50be621 100644
--- a/backend/server/src/container.rs
+++ b/backend/server/src/container.rs
@@ -9,7 +9,10 @@ use auth::{
         exchange_auth_code_use_case::ExchangeAuthCodeUseCaseImpl,
         get_auth_url_use_case::LoginUseCaseImpl,
     },
-    framework::oidc::auth_oidc_service_impl::AuthOidcServiceImpl,
+    framework::{
+        db::user_db_service_impl::UserDbServiceImpl,
+        oidc::auth_oidc_service_impl::AuthOidcServiceImpl,
+    },
 };
 use image::{
     adapter::{
@@ -60,7 +63,8 @@ impl Container {
             oidc_configuration.redirect_url.clone(),
             http_client,
         ));
-        let auth_repository = Arc::new(AuthRepositoryImpl::new(auth_oidc_service));
+        let user_db_service = Arc::new(UserDbServiceImpl::new(db_pool.clone()));
+        let auth_repository = Arc::new(AuthRepositoryImpl::new(user_db_service, auth_oidc_service));
         let get_auth_url_use_case = Arc::new(LoginUseCaseImpl::new(auth_repository.clone()));
         let exchange_auth_code_use_case =
             Arc::new(ExchangeAuthCodeUseCaseImpl::new(auth_repository.clone()));