diff --git a/src/middleware/graphql-server/index.test.ts b/src/middleware/graphql-server/index.test.ts
index 51974626..4f4f55ec 100644
--- a/src/middleware/graphql-server/index.test.ts
+++ b/src/middleware/graphql-server/index.test.ts
@@ -8,6 +8,9 @@ import {
 import { Hono } from '@/hono'
 import { errorMessages, graphqlServer } from '@/middleware/graphql-server'
 
+// Do not show `console.error` messages
+jest.spyOn(console, 'error').mockImplementation()
+
 describe('errorMessages', () => {
   const messages = errorMessages(['message a', 'message b'])
   expect(messages).toEqual({
diff --git a/src/middleware/graphql-server/index.ts b/src/middleware/graphql-server/index.ts
index 1bc5294b..d0455635 100644
--- a/src/middleware/graphql-server/index.ts
+++ b/src/middleware/graphql-server/index.ts
@@ -55,6 +55,7 @@ export const graphqlServer = (options: Options) => {
       params = await getGraphQLParams(c.req)
     } catch (e) {
       if (e instanceof Error) {
+        console.error(`${e.stack || e.message}`)
         c.res = c.json(errorMessages([e.message], [e]), 400)
       }
       return
@@ -83,6 +84,7 @@ export const graphqlServer = (options: Options) => {
     } catch (syntaxError: unknown) {
       // Return 400: Bad Request if any syntax errors errors exist.
       if (syntaxError instanceof Error) {
+        console.error(`${syntaxError.stack || syntaxError.message}`)
         const e = new GraphQLError(syntaxError.message, {
           originalError: syntaxError,
         })
@@ -135,6 +137,7 @@ export const graphqlServer = (options: Options) => {
       })
     } catch (contextError: unknown) {
       if (contextError instanceof Error) {
+        console.error(`${contextError.stack || contextError.message}`)
         const e = new GraphQLError(contextError.message, {
           originalError: contextError,
           nodes: documentAST,
@@ -237,4 +240,4 @@ export const errorMessages = (
   }
 }
 
-export const graphiQLResponse = () => {}
+// export const graphiQLResponse = () => {}
diff --git a/src/middleware/graphql-server/parse-body.ts b/src/middleware/graphql-server/parse-body.ts
index 02c28392..ea827e67 100644
--- a/src/middleware/graphql-server/parse-body.ts
+++ b/src/middleware/graphql-server/parse-body.ts
@@ -8,6 +8,9 @@ export async function parseBody(req: Request): Promise<{ [param: string]: unknow
       try {
         return await req.json()
       } catch (e) {
+        if (e instanceof Error) {
+          console.error(`${e.stack || e.message}`)
+        }
         throw Error(`POST body sent invalid JSON: ${e}`)
       }
     case 'application/x-www-form-urlencoded':