diff --git a/src/main/java/org/ntlab/tampoposerver/repositories/FriendRepository.java b/src/main/java/org/ntlab/tampoposerver/repositories/FriendRepository.java
index 48058a2..38340a7 100644
--- a/src/main/java/org/ntlab/tampoposerver/repositories/FriendRepository.java
+++ b/src/main/java/org/ntlab/tampoposerver/repositories/FriendRepository.java
@@ -3,7 +3,9 @@
 import org.ntlab.tampoposerver.models.FriendPair;
 import org.springframework.stereotype.Repository;
 
+import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 @Repository
@@ -65,4 +67,17 @@
         FriendPair removedPair = friends.remove(pairId);
         return removedPair != null;
     }
+
+    // 指定ユーザーとフレンドの一覧を返す
+    public List<String> findFriendsByUserId(String userId) {
+        List<String> result = new ArrayList<>();
+        for (FriendPair pair : friends.values()) {
+            if (pair.getUser0Id().equals(userId)) {
+                result.add(pair.getUser1Id());
+            } else if (pair.getUser1Id().equals(userId)) {
+                result.add(pair.getUser0Id());
+            }
+        }
+        return result;
+    }
 }