diff --git a/src/endpoints/forms.tsp b/src/endpoints/forms.tsp
index 4a08d6e..a0fc063 100644
--- a/src/endpoints/forms.tsp
+++ b/src/endpoints/forms.tsp
@@ -253,6 +253,21 @@ namespace Forms {
         @statusCode statusCode: 400 | 401 | 403 | 404 | 500;
         @body body: Error;
       };
+
+      @route("/labels")
+      @put
+      @summary("回答についているラベルの置き換え")
+      op replace(
+        @path answerId: uint32,
+        @body body: {
+          labels: Label[];
+        },
+      ): {
+        @statusCode statusCode: 200;
+      } | {
+        @statusCode statusCode: 400 | 401 | 403 | 500;
+        @body body: Error;
+      };
     }
 
     @route("/comment")
diff --git a/src/models/form.tsp b/src/models/form.tsp
index 3679a6c..c441d1e 100644
--- a/src/models/form.tsp
+++ b/src/models/form.tsp
@@ -87,6 +87,7 @@ model Answer {
     timestamp: utcDateTime;
     commented_by: User;
   }[];
+  labels: Label[];
 }
 
 model Label {