diff --git a/src/main/java/org/ntlab/citrusserver/repositories/BookManager.java b/src/main/java/org/ntlab/citrusserver/repositories/BookManager.java
index 7185830..b5937f1 100644
--- a/src/main/java/org/ntlab/citrusserver/repositories/BookManager.java
+++ b/src/main/java/org/ntlab/citrusserver/repositories/BookManager.java
@@ -95,7 +95,7 @@
 
     public void deleteAllBooks(String accountId)
     {
-        booksMap.get(accountId).clear();
+        booksMap.remove(accountId);
     }
 
     //（（（　目標・振り返りは省略　）））
diff --git a/src/main/java/org/ntlab/citrusserver/resources/BooksRest.java b/src/main/java/org/ntlab/citrusserver/resources/BooksRest.java
index 6289f93..3398b0b 100644
--- a/src/main/java/org/ntlab/citrusserver/resources/BooksRest.java
+++ b/src/main/java/org/ntlab/citrusserver/resources/BooksRest.java
@@ -6,6 +6,7 @@
 import org.ntlab.citrusserver.entities.Book;
 import org.ntlab.citrusserver.repositories.AccountManager;
 import org.ntlab.citrusserver.repositories.BookManager;
+import org.ntlab.citrusserver.repositories.TodoManager;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Component;
 
@@ -20,11 +21,13 @@
 
     private final BookManager bookManager;
     private final AccountManager accountManager;
+    private final TodoManager todoManager;
     @Autowired  // スプリングブートにいうサイン
-    public BooksRest(BookManager bm, AccountManager ac){//public クラス名（）がコンストラクタ
+    public BooksRest(BookManager bm, AccountManager ac, TodoManager tm){//public クラス名（）がコンストラクタ
 
         bookManager = bm;
         accountManager = ac;
+        todoManager = tm;
     }
 
 
@@ -111,6 +114,7 @@
                 throw new WebApplicationException(response.build());
             }
             else{
+                todoManager.deleteAllTodosByBookId(account_id, book_id);//削除時、Todoも消す
                 bookManager.deleteBook(account_id, book_id);
                 return "success";
             }
@@ -229,4 +233,9 @@
             }
         }
     }
+
+    ///---------------------------------------------------------------------
+    ///private
+    ///---------------------------------------------------------------------
+
 }
\ No newline at end of file