diff --git a/backend/feature/post/src/adapter/delivery/create_post_request_dto.rs b/backend/feature/post/src/adapter/delivery/create_post_request_dto.rs
index 9c273d2..053b6a6 100644
--- a/backend/feature/post/src/adapter/delivery/create_post_request_dto.rs
+++ b/backend/feature/post/src/adapter/delivery/create_post_request_dto.rs
@@ -12,8 +12,8 @@ pub struct CreatePostRequestDto {
     pub content: String,
     pub label_ids: Vec<i32>,
 
-    #[schema(required)]
-    pub published_time: Option<i64>,
+    #[schema(required, format = DateTime)]
+    pub published_time: Option<String>,
 }
 
 impl CreatePostRequestDto {
@@ -28,8 +28,8 @@ impl CreatePostRequestDto {
                 labels: Vec::new(),
                 published_time: self
                     .published_time
-                    .map(|micros| DateTime::<Utc>::from_timestamp_micros(micros))
-                    .flatten(),
+                    .and_then(|time_str| DateTime::parse_from_rfc3339(&time_str).ok())
+                    .map(|dt| dt.with_timezone(&Utc)),
             },
             content: self.content,
         }
diff --git a/backend/feature/post/src/adapter/delivery/post_info_response_dto.rs b/backend/feature/post/src/adapter/delivery/post_info_response_dto.rs
index dd33091..176b9c3 100644
--- a/backend/feature/post/src/adapter/delivery/post_info_response_dto.rs
+++ b/backend/feature/post/src/adapter/delivery/post_info_response_dto.rs
@@ -12,7 +12,9 @@ pub struct PostInfoResponseDto {
     pub description: String,
     pub preview_image_url: String,
     pub labels: Vec<LabelResponseDto>,
-    pub published_time: Option<i64>,
+
+    #[schema(format = DateTime)]
+    pub published_time: Option<String>,
 }
 
 impl From<PostInfo> for PostInfoResponseDto {
@@ -27,9 +29,7 @@ impl From<PostInfo> for PostInfoResponseDto {
                 .into_iter()
                 .map(LabelResponseDto::from)
                 .collect(),
-            published_time: entity
-                .published_time
-                .map(|datetime| datetime.timestamp_micros()),
+            published_time: entity.published_time.map(|datetime| datetime.to_rfc3339()),
         }
     }
 }
diff --git a/backend/feature/post/src/adapter/delivery/update_post_request_dto.rs b/backend/feature/post/src/adapter/delivery/update_post_request_dto.rs
index f7f3683..7ae2128 100644
--- a/backend/feature/post/src/adapter/delivery/update_post_request_dto.rs
+++ b/backend/feature/post/src/adapter/delivery/update_post_request_dto.rs
@@ -12,8 +12,8 @@ pub struct UpdatePostRequestDto {
     pub content: String,
     pub label_ids: Vec<i32>,
 
-    #[schema(required)]
-    pub published_time: Option<i64>,
+    #[schema(required, format = DateTime)]
+    pub published_time: Option<String>,
 }
 
 impl UpdatePostRequestDto {
@@ -28,8 +28,8 @@ impl UpdatePostRequestDto {
                 labels: Vec::new(),
                 published_time: self
                     .published_time
-                    .map(|micros| DateTime::<Utc>::from_timestamp_micros(micros))
-                    .flatten(),
+                    .and_then(|time_str| DateTime::parse_from_rfc3339(&time_str).ok())
+                    .map(|dt| dt.with_timezone(&Utc)),
             },
             content: self.content,
         }
diff --git a/frontend/src/lib/post/adapter/gateway/postInfoResponseDto.ts b/frontend/src/lib/post/adapter/gateway/postInfoResponseDto.ts
index 1ada6b5..e6393b2 100644
--- a/frontend/src/lib/post/adapter/gateway/postInfoResponseDto.ts
+++ b/frontend/src/lib/post/adapter/gateway/postInfoResponseDto.ts
@@ -8,7 +8,7 @@ export const PostInfoResponseSchema = z.object({
 	description: z.string(),
 	preview_image_url: z.url(),
 	labels: z.array(LabelResponseSchema),
-	published_time: z.number().int()
+	published_time: z.iso.datetime()
 });
 
 export class PostInfoResponseDto {
@@ -43,7 +43,7 @@ export class PostInfoResponseDto {
 			description: parsedJson.description,
 			previewImageUrl: new URL(parsedJson.preview_image_url),
 			labels: parsedJson.labels.map((label) => LabelResponseDto.fromJson(label)),
-			publishedTime: new Date(parsedJson.published_time / 1000)
+			publishedTime: new Date(parsedJson.published_time)
 		});
 	}