diff --git a/src/main/java/org/ntlab/citrusserver/repositories/BookManager.java b/src/main/java/org/ntlab/citrusserver/repositories/BookManager.java
index ecf2664..7185830 100644
--- a/src/main/java/org/ntlab/citrusserver/repositories/BookManager.java
+++ b/src/main/java/org/ntlab/citrusserver/repositories/BookManager.java
@@ -32,14 +32,12 @@
     //本の一覧を返す
     public HashMap<Integer, Book> getBooks(String accountId)
     {
-        if(accountManager.getAccount(accountId) == null) return null; //アカウントが存在しない
         return booksMap.get(accountId);
     }
 
     //本の新規作成
     public Book createBook(String accountId, String title, String color, Boolean publicity)
     {
-        if(accountManager.getAccount(accountId) == null) return null; //アカウントが存在しない
         if(!booksMap.containsKey(accountId)){
             booksMap.put(accountId, new HashMap<>());
         }
@@ -54,19 +52,13 @@
     //本の情報を取得
     public Book getBook(String accountId, Integer bookId)
     {
-        if(accountManager.getAccount(accountId) == null) return null; //アカウントが存在しない
         return booksMap.get(accountId).get(bookId);
     }
 
     //本の削除
-    public int deleteBook(String accountId, Integer bookId)
+    public void deleteBook(String accountId, Integer bookId)
     {
-        if(accountManager.getAccount(accountId) == null) return -1; //アカウントが存在しない
-        else
-        {
-            booksMap.get(accountId).remove(bookId);
-            return 1;
-        }
+        booksMap.get(accountId).remove(bookId);
     }
 
     //（（（　いいねは省略　）））
@@ -79,51 +71,39 @@
     }
 
     //本のタイトルを変更
-    public int putTitle(String accountId, Integer bookId, String title)
+    public void putTitle(String accountId, Integer bookId, String title)
     {
-        if(accountManager.getAccount(accountId) == null) return -1; //アカウントが存在しない
-        else
-        {
             booksMap.get(accountId).get(bookId).setTitle(title);
-            return 1;
-        }
-
     }
 
     //本の公開情報を返す
     public Boolean getPublicity(String accountId, Integer bookId)
     {
-        if(accountManager.getAccount(accountId) == null) return null; //アカウントが存在しない
         return booksMap.get(accountId).get(bookId).getPublicity();
     }
 
     //公開情報を変更する
-    public int putPublicity(String accountId, Integer bookId, Boolean publicity)
+    public void putPublicity(String accountId, Integer bookId, Boolean publicity)
     {
         Account account = accountManager.getAccount(accountId);
         Book book = booksMap.get(accountId).get(bookId);
-        if(account == null) return -1; //アカウントが存在しない
-        else
-        {
-            if(book.getPublicity() == publicity) return 1;//変更が無ければ終了
-            book.setPublicity(publicity);
-            notifyListener(account, book);
-            return 1;
-        }
+        if(book.getPublicity() == publicity) return;//変更が無ければ終了
+        book.setPublicity(publicity);
+        notifyListener(account, book);
+
+    }
+
+    public void deleteAllBooks(String accountId)
+    {
+        booksMap.get(accountId).clear();
     }
 
     //（（（　目標・振り返りは省略　）））
 
     //本の色を変更する
-    public int putColor(String accountId, Integer bookId, String color)
+    public void putColor(String accountId, Integer bookId, String color)
     {
-        if(accountManager.getAccount(accountId) == null) return -1; //アカウントが存在しない
-        else
-        {
             booksMap.get(accountId).get(bookId).setColor(color);
-            return 1;
-        }
-
     }
 
     //---------------------------------------------------------------------------------