diff --git a/app/src/main/java/com/example/citrusclient/rest/FavoritesRest.java b/app/src/main/java/com/example/citrusclient/rest/FavoritesRest.java
index cffd5df..30b2273 100644
--- a/app/src/main/java/com/example/citrusclient/rest/FavoritesRest.java
+++ b/app/src/main/java/com/example/citrusclient/rest/FavoritesRest.java
@@ -3,7 +3,7 @@
 import com.example.citrusclient.models.Book;
 
 import java.util.HashMap;
-import java.util.HashSet;
+import java.util.List;
 
 import retrofit2.Call;
 import retrofit2.http.DELETE;
@@ -26,7 +26,7 @@
     //主{account_id}がいいねした誰か{other_account_id}の本の一覧
     @FormUrlEncoded
     @GET("accounts/{account_id}/favorites/{other_account_id}")
-    Call<HashSet<Integer>> getFavoritesBooksById(
+    Call<List<Integer>> getFavoritesBooksById(
             @Path("account_id") String accountId,
             @Path("other_account_id") String otherAccountId,
             @Query("token") String token
@@ -35,7 +35,7 @@
     //主{account_id}のある本{book_id}をいいねした人の一覧
     @FormUrlEncoded
     @GET("accounts/{account_id}/books/{book_id}/favorited")
-    Call<HashSet<String>> getFavoritedAccount(
+    Call<List<String>> getFavoritedAccount(
             @Path("account_id") String accountId,
             @Path("book_id") Integer bookId,
             @Query("token") String token
diff --git a/app/src/main/java/com/example/citrusclient/viewmodels/FavoritesViewModel.java b/app/src/main/java/com/example/citrusclient/viewmodels/FavoritesViewModel.java
index 0ba119b..bdae58c 100644
--- a/app/src/main/java/com/example/citrusclient/viewmodels/FavoritesViewModel.java
+++ b/app/src/main/java/com/example/citrusclient/viewmodels/FavoritesViewModel.java
@@ -4,7 +4,7 @@
 import com.example.citrusclient.rest.FavoritesRest;
 
 import java.util.HashMap;
-import java.util.HashSet;
+import java.util.List;
 
 import androidx.lifecycle.MutableLiveData;
 import androidx.lifecycle.ViewModel;
@@ -19,8 +19,8 @@
     private final FavoritesRest favoritesRest;
 
     private final MutableLiveData<HashMap<String, HashMap<Integer, Book>>> favoritesBooksLiveData;
-    private final MutableLiveData<HashSet<Integer>> favoritesBookIdLiveData;
-    private final MutableLiveData<HashSet<String>> favoritedAccountsLiveData;
+    private final MutableLiveData<List<Integer>> favoritesBookIdLiveData;
+    private final MutableLiveData<List<String>> favoritedAccountsLiveData;
 
     public FavoritesViewModel(){
         this.retrofit = new Retrofit.Builder()
@@ -33,8 +33,8 @@
         this.favoritedAccountsLiveData = new MutableLiveData<>();
     }
     public MutableLiveData<HashMap<String, HashMap<Integer, Book>>> getFavoritesBooksLiveData(){return favoritesBooksLiveData;}
-    public MutableLiveData<HashSet<Integer>> getFavoritesBookIdLiveData(){return favoritesBookIdLiveData;}
-    public MutableLiveData<HashSet<String>> getFavoritedAccountsLiveData(){return  favoritedAccountsLiveData;}
+    public MutableLiveData<List<Integer>> getFavoritesBookIdLiveData(){return favoritesBookIdLiveData;}
+    public MutableLiveData<List<String>> getFavoritedAccountsLiveData(){return  favoritedAccountsLiveData;}
 
     public void loadFavoritesBooks(String accountId, String token){
         Call<HashMap<String, HashMap<Integer, Book>>> call = favoritesRest.getFavoritesBooks(accountId,token);
@@ -55,10 +55,10 @@
     }
 
     public void loadFavoritesBookId(String accountId, String otherAccountId, String token){
-        Call<HashSet<Integer>> call = favoritesRest.getFavoritesBooksById(accountId,otherAccountId,token);
-        call.enqueue(new Callback<HashSet<Integer>>() {
+        Call<List<Integer>> call = favoritesRest.getFavoritesBooksById(accountId,otherAccountId,token);
+        call.enqueue(new Callback<List<Integer>>() {
             @Override
-            public void onResponse(Call<HashSet<Integer>> call, Response<HashSet<Integer>> response) {
+            public void onResponse(Call<List<Integer>> call, Response<List<Integer>> response) {
                 if(response.isSuccessful()){
                     System.out.println("success : getFavoritesBooksById");
                     favoritesBookIdLiveData.setValue(response.body());
@@ -66,17 +66,17 @@
             }
 
             @Override
-            public void onFailure(Call<HashSet<Integer>> call, Throwable t) {
+            public void onFailure(Call<List<Integer>> call, Throwable t) {
                 System.out.println("NetworkError : getFavoritesBooksById" + t);
             }
         });
     }
 
     public void loadFavoritedAccounts(String accountId, Integer bookId, String token){
-        Call<HashSet<String>> call = favoritesRest.getFavoritedAccount(accountId,bookId,token);
-        call.enqueue(new Callback<HashSet<String>>() {
+        Call<List<String>> call = favoritesRest.getFavoritedAccount(accountId,bookId,token);
+        call.enqueue(new Callback<List<String>>() {
             @Override
-            public void onResponse(Call<HashSet<String>> call, Response<HashSet<String>> response) {
+            public void onResponse(Call<List<String>> call, Response<List<String>> response) {
                 if(response.isSuccessful()){
                     System.out.println("success : getFavoritedAccount");
                     favoritedAccountsLiveData.setValue(response.body());
@@ -84,7 +84,7 @@
             }
 
             @Override
-            public void onFailure(Call<HashSet<String>> call, Throwable t) {
+            public void onFailure(Call<List<String>> call, Throwable t) {
                 System.out.println("NetworkError : getFavoritedAccount" + t);
             }
         });