diff --git a/src/main/java/org/ntlab/citrusserver/repositories/BookManager.java b/src/main/java/org/ntlab/citrusserver/repositories/BookManager.java
index ecf2664..eb656ad 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 +71,34 @@
     }
 
     //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);
+
     }
 
     //（（（　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;
-        }
-
     }
 
     //---------------------------------------------------------------------------------
diff --git a/src/main/java/org/ntlab/citrusserver/resources/BooksRest.java b/src/main/java/org/ntlab/citrusserver/resources/BooksRest.java
index 3386151..6289f93 100644
--- a/src/main/java/org/ntlab/citrusserver/resources/BooksRest.java
+++ b/src/main/java/org/ntlab/citrusserver/resources/BooksRest.java
@@ -36,8 +36,7 @@
     @Produces(MediaType.APPLICATION_JSON)
     public  HashMap<Integer, Book> getBooks(@PathParam("account_id") String account_id, @QueryParam("token") String token){
 
-        HashMap<Integer, Book> books = bookManager.getBooks(account_id);
-        if(books == null){
+        if(accountManager.getAccount(account_id) == null){
             var response = Response.status(Response.Status.NOT_FOUND).entity("アカウントが見つかりません");
             throw new WebApplicationException(response.build());
         }
@@ -47,7 +46,7 @@
                 throw new WebApplicationException(response.build());
             }
             else{
-                return books;
+                return bookManager.getBooks(account_id);
             }
         }
     }
@@ -58,8 +57,7 @@
     @Consumes(MediaType.APPLICATION_FORM_URLENCODED)  // postmanのbodyに入力する値がある時
     public Book createBook(@PathParam("account_id") String account_id, @FormParam("title") String title, @FormParam("color") String color, @FormParam("publicity") Boolean publicity, @FormParam("token") String token) {
 
-        Book book = bookManager.createBook(account_id, title, color, publicity);
-        if (book == null){
+        if (accountManager.getAccount(account_id) == null){
             var response = Response.status(Response.Status.NOT_FOUND).entity("アカウントが見つかりません");
             throw new WebApplicationException(response.build());
         }
@@ -69,7 +67,7 @@
                 throw new WebApplicationException(response.build());
             }
             else {
-                return book;
+                return bookManager.createBook(account_id, title, color, publicity);
             }
         }
     }
@@ -82,8 +80,7 @@
     @Produces(MediaType.APPLICATION_JSON)
     public Book getBook(@PathParam("account_id") String account_id, @PathParam("book_id") Integer book_id, @QueryParam("token") String token){
 
-        Book book = bookManager.getBook(account_id, book_id);
-        if (book == null){
+        if (accountManager.getAccount(account_id) == null){
             var response = Response.status(Response.Status.NOT_FOUND).entity("アカウントが見つかりません");
             throw new WebApplicationException(response.build());
         }
@@ -93,7 +90,7 @@
                 throw new WebApplicationException(response.build());
             }
             else{
-                return book;
+                return bookManager.getBook(account_id, book_id);
             }
         }
     }
@@ -104,8 +101,7 @@
     @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
     public String deleteBook(@PathParam("account_id") String account_id, @PathParam("book_id") Integer book_id, @QueryParam("token") String token){
 
-        int check = bookManager.deleteBook(account_id, book_id);
-        if(check == -1){
+        if(accountManager.getAccount(account_id) == null){
             var response = Response.status(Response.Status.NOT_FOUND).entity("アカウントが見つかりません");
             throw new WebApplicationException(response.build());
         }
@@ -115,6 +111,7 @@
                 throw new WebApplicationException(response.build());
             }
             else{
+                bookManager.deleteBook(account_id, book_id);
                 return "success";
             }
         }
@@ -127,8 +124,7 @@
     @Produces(MediaType.TEXT_PLAIN)
     public String getTitle(@PathParam("account_id") String account_id, @PathParam("book_id") Integer book_id, @QueryParam("token") String token){
 
-        String str = bookManager.getTitle(account_id, book_id);
-        if (str == null) {
+        if (accountManager.getAccount(account_id) == null) {
             var response = Response.status(Response.Status.NOT_FOUND).entity("アカウントが見つかりません");
             throw new WebApplicationException(response.build());
         }
@@ -138,7 +134,7 @@
                 throw new WebApplicationException(response.build());
             }
             else{
-                return str;
+                return bookManager.getTitle(account_id, book_id);
             }
         }
     }
@@ -150,8 +146,7 @@
     @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
     public String putTitle(@PathParam("account_id") String account_id, @PathParam("book_id") Integer book_id, @FormParam("title") String title, @FormParam("token") String token){
 
-        int check = bookManager.putTitle(account_id, book_id, title);
-        if(check == -1){
+        if(accountManager.getAccount(account_id) == null){
             var response = Response.status(Response.Status.NOT_FOUND).entity("アカウントが見つかりません");
             throw new WebApplicationException(response.build());
         }
@@ -161,6 +156,7 @@
                 throw new WebApplicationException(response.build());
             }
             else{
+                bookManager.putTitle(account_id, book_id, title);
                 return "success";
             }
         }
@@ -173,8 +169,7 @@
     @Produces(MediaType.TEXT_PLAIN)
     public Boolean getPublicity(@PathParam("account_id") String account_id, @PathParam("book_id") Integer book_id, @QueryParam("token") String token){
 
-        Boolean publicity = bookManager.getPublicity(account_id, book_id);
-        if (publicity == null) {
+        if (accountManager.getAccount(account_id) == null) {
             var response = Response.status(Response.Status.NOT_FOUND).entity("アカウントが見つかりません");
             throw new WebApplicationException(response.build());
         }
@@ -184,7 +179,7 @@
                 throw new WebApplicationException(response.build());
             }
             else{
-                return publicity;
+                return bookManager.getPublicity(account_id, book_id);
             }
         }
     }
@@ -196,8 +191,7 @@
     @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
     public String putPublicity(@PathParam("account_id") String account_id, @PathParam("book_id") Integer book_id, @FormParam("publicity") Boolean publicity, @FormParam("token") String token){
 
-        int check = bookManager.putPublicity(account_id, book_id, publicity);
-        if(check == -1){
+        if(accountManager.getAccount(account_id) == null){
             var response = Response.status(Response.Status.NOT_FOUND).entity("アカウントが見つかりません");
             throw new WebApplicationException(response.build());
         }
@@ -207,6 +201,7 @@
                 throw new WebApplicationException(response.build());
             }
             else{
+                bookManager.putPublicity(account_id, book_id, publicity);
                 return "success";
             }
         }
@@ -219,8 +214,7 @@
     @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
     public String putColor(@PathParam("account_id") String account_id, @PathParam("book_id") Integer book_id, @FormParam("color") String color, @FormParam("token") String token){
 
-        int check = bookManager.putColor(account_id, book_id, color);
-        if(check == -1){
+        if(accountManager.getAccount(account_id) == null){
             var response = Response.status(Response.Status.NOT_FOUND).entity("アカウントが見つかりません");
             throw new WebApplicationException(response.build());
         }
@@ -230,6 +224,7 @@
                 throw new WebApplicationException(response.build());
             }
             else{
+                bookManager.putColor(account_id, book_id, color);
                 return "success";
             }
         }