diff --git a/src/main/java/org/ntlab/citrusserver/resources/BooksRest.java b/src/main/java/org/ntlab/citrusserver/resources/BooksRest.java
index 99802ce..49f2e4a 100644
--- a/src/main/java/org/ntlab/citrusserver/resources/BooksRest.java
+++ b/src/main/java/org/ntlab/citrusserver/resources/BooksRest.java
@@ -2,6 +2,7 @@
 
 import jakarta.ws.rs.*;
 import jakarta.ws.rs.core.MediaType;
+import jakarta.ws.rs.core.Response;
 import org.ntlab.citrusserver.entities.Book;
 import org.ntlab.citrusserver.repositories.AccountManager;
 import org.ntlab.citrusserver.repositories.BookManager;
@@ -34,8 +35,13 @@
     @GET
     @Produces(MediaType.APPLICATION_JSON)
     public  HashMap<Integer, Book> getBooks(@PathParam("account_id") String account_id, @QueryParam("token") String token){
-        if(!accountManager.checkToken(account_id, token)) return null;
-        return bookManager.getBooks(account_id, 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{
+            return bookManager.getBooks(account_id, token);
+        }
     }
 
     @Path("/{account_id}/books")
@@ -43,8 +49,13 @@
     @Produces(MediaType.APPLICATION_JSON)  // intとかstringとかがたくさん返ってくるから、json public voidじゃないときは、返さなあかんから、 @Produces(MediaType.APPLICATION_JSON) これがいる
     @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) {
-        if(!accountManager.checkToken(account_id, token)) return null;
-        return bookManager.createBook(account_id, title, color, publicity, 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{
+            return bookManager.createBook(account_id, title, color, publicity, token);
+        }
     }
 
 
@@ -54,8 +65,13 @@
     @GET
     @Produces(MediaType.APPLICATION_JSON)
     public Book getBook(@PathParam("account_id") String account_id, @PathParam("book_id") Integer book_id, @QueryParam("token") String token){
-        if(!accountManager.checkToken(account_id, token)) return null;
-        return bookManager.getBook(account_id, book_id, 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{
+            return bookManager.getBook(account_id, book_id, token);
+        }
     }
   /// 本の削除
     @Path("/{account_id}/books/{book_id}")
@@ -72,8 +88,13 @@
     @GET
     @Produces(MediaType.TEXT_PLAIN)
     public String getTitle(@PathParam("account_id") String account_id, @PathParam("book_id") Integer book_id, @QueryParam("token") String token){
-        if(!accountManager.checkToken(account_id, token)) return null;
-        return bookManager.getTitle(account_id, book_id, 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{
+            return bookManager.getTitle(account_id, book_id, token);
+        }
     }
 
   /// 本のタイトル変更
@@ -91,8 +112,13 @@
     @GET
     @Produces(MediaType.TEXT_PLAIN)
     public Boolean getPublicity(@PathParam("account_id") String account_id, @PathParam("book_id") Integer book_id, @QueryParam("token") String token){
-        if(!accountManager.checkToken(account_id, token)) return null;
-        return bookManager.getPublicity(account_id, book_id, 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{
+            return bookManager.getPublicity(account_id, book_id, token);
+        }
     }
 
   /// 公開情報を変更する
@@ -105,7 +131,7 @@
     }
 
 /// /accounts/{account_id}/books/{book_id}/color
-  /// 公開情報を変更する
+  /// 色を変更する
     @Path("/{account_id}/books/{book_id}/color")
     @PUT
     @Consumes(MediaType.APPLICATION_FORM_URLENCODED)