diff --git a/src/main/java/org/ntlab/citrusserver/resources/BooksRest.java b/src/main/java/org/ntlab/citrusserver/resources/BooksRest.java
index 2695eb9..934dc2d 100644
--- a/src/main/java/org/ntlab/citrusserver/resources/BooksRest.java
+++ b/src/main/java/org/ntlab/citrusserver/resources/BooksRest.java
@@ -40,7 +40,14 @@
             throw new WebApplicationException(response.build());
         }
         else{
-            return bookManager.getBooks(account_id);
+            if(bookManager.getBooks(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());
+            }
+            else{
+                return bookManager.getBooks(account_id);
+            }
+
         }
     }
 
@@ -70,7 +77,13 @@
             throw new WebApplicationException(response.build());
         }
         else{
-            return bookManager.getBook(account_id, book_id);
+            if (bookManager.getBook(account_id, book_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());
+            }
+            else{
+                return bookManager.getBook(account_id, book_id);
+            }
         }
     }
   /// 本の削除
@@ -78,14 +91,19 @@
     @DELETE
     @Produces(MediaType.TEXT_PLAIN)
     @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
-    public String deleteTodoById(@PathParam("account_id") String account_id, @PathParam("book_id") Integer book_id, @QueryParam("token") String token){
+    public String deleteBook(@PathParam("account_id") String account_id, @PathParam("book_id") Integer book_id, @QueryParam("token") String token){
         if(!accountManager.checkToken(account_id, token)) {
             var response = Response.status(Response.Status.FORBIDDEN).entity("認証失敗");
             throw new WebApplicationException(response.build());
         }
         else{
-            bookManager.deleteBook(account_id, book_id);
-            return "success";
+            if(bookManager.deleteBook(account_id, book_id) == -1){
+                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());
+            }
+            else{
+                return "success";
+            }
         }
     }
 
@@ -100,7 +118,13 @@
             throw new WebApplicationException(response.build());
         }
         else{
-            return bookManager.getTitle(account_id, book_id);
+            if (bookManager.getTitle(account_id, book_id) == null) {
+                var response = Response.status(Response.Status.FORBIDDEN).entity("アカウントが見つかりません");
+                throw new WebApplicationException(response.build());
+            }
+            else{
+                return (bookManager.getTitle(account_id, book_id));
+            }
         }
     }
 
@@ -115,8 +139,13 @@
             throw new WebApplicationException(response.build());
         }
         else{
-            bookManager.putTitle(account_id, book_id, title);
-            return "success";
+            if(bookManager.putTitle(account_id, book_id, title) == -1){
+                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());
+            }
+            else{
+                return "success";
+            }
         }
     }
 
@@ -131,7 +160,13 @@
             throw new WebApplicationException(response.build());
         }
         else{
-            return bookManager.getPublicity(account_id, book_id);
+            if (bookManager.getPublicity(account_id, book_id) == null) {
+                var response = Response.status(Response.Status.FORBIDDEN).entity("アカウントが見つかりません");
+                throw new WebApplicationException(response.build());
+            }
+            else{
+                return bookManager.getPublicity(account_id, book_id);
+            }
         }
     }
 
@@ -146,8 +181,13 @@
             throw new WebApplicationException(response.build());
         }
         else{
-            bookManager.putPublicity(account_id, book_id, publicity);
-            return "success";
+            if(bookManager.putPublicity(account_id, book_id, publicity) == -1){
+                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());
+            }
+            else{
+                return "success";
+            }
         }
     }
 
@@ -162,8 +202,13 @@
             throw new WebApplicationException(response.build());
         }
         else{
-            bookManager.putColor(account_id, book_id, color);
-            return "success";
+            if(bookManager.putColor(account_id, book_id, color) == -1){
+                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());
+            }
+            else{
+                return "success";
+            }
         }
     }
 }
\ No newline at end of file