diff --git a/src/main/java/org/ntlab/nemophila/resources/accounts/FriendsRest.java b/src/main/java/org/ntlab/nemophila/resources/accounts/FriendsRest.java
index 2533e4b..5513326 100644
--- a/src/main/java/org/ntlab/nemophila/resources/accounts/FriendsRest.java
+++ b/src/main/java/org/ntlab/nemophila/resources/accounts/FriendsRest.java
@@ -82,8 +82,8 @@
         HashSet<Account> otherFriends = otherFriendManager.getFriends();  //fidのAccountのfriendsを取得
 
         if (myFriends.contains(otherAc) || otherFriends.contains(myAc)) {
-            myFriends.remove(otherAc);
-            otherFriends.remove(myAc);
+            myFriendManager.removeFriend(otherAc);
+            otherFriendManager.removeFriend(myAc);
         } else {
             var response = Response.status(Response.Status.NO_CONTENT);
             response.status(400).entity("リクエストが不正である");