diff --git a/src/api/endpoints/auth/session/show.js b/src/api/endpoints/auth/session/show.js
index 9072edc1c0..e161d9e576 100644
--- a/src/api/endpoints/auth/session/show.js
+++ b/src/api/endpoints/auth/session/show.js
@@ -27,7 +27,7 @@ import serialize from '../../../serializers/auth-session';
  *           properties:
  *             created_at:
  *               type: string
- *               format: date
+ *               format: date-time
  *               description: Date and time of the session creation
  *             app_id:
  *               type: string
diff --git a/swagger.js b/swagger.js
index 0deff2c5a3..a4122350fe 100644
--- a/swagger.js
+++ b/swagger.js
@@ -99,11 +99,12 @@ const defaultSwagger = {
         },
         "birthday": {
           "type": "string",
+          "format": "date",
           "description": "誕生日"
         },
         "created_at": {
           "type": "string",
-          "format": "date",
+          "format": "date-time",
           "description": "アカウント作成日時"
         },
         "drive_capacity": {
@@ -161,7 +162,7 @@ const defaultSwagger = {
       "properties": {
         "created_at": {
           "type": "string",
-          "format": "date",
+          "format": "date-time",
           "description": "アプリケーションの作成日時"
         },
         "user_id": {