diff --git a/src/main/java/org/ntlab/tampoposerver/resources/FriendRequestsResource.java b/src/main/java/org/ntlab/tampoposerver/resources/FriendRequestsResource.java
index aca1914..2630cab 100644
--- a/src/main/java/org/ntlab/tampoposerver/resources/FriendRequestsResource.java
+++ b/src/main/java/org/ntlab/tampoposerver/resources/FriendRequestsResource.java
@@ -61,7 +61,7 @@
             return Response.status(Response.Status.BAD_REQUEST).build();
         }
         // 201(フレンドリクエスト作成)
-        return Response.status(Response.Status.OK).entity(created.getId()).build();
+        return Response.status(Response.Status.OK).entity(Integer.toString(created.getId())).build();
     }
 
     @Path("/{friend-request-id}")