diff --git a/kenall.go b/kenall.go
index a0614ef..999159e 100644
--- a/kenall.go
+++ b/kenall.go
@@ -3,10 +3,12 @@ package kenall
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
 	"net/http"
+	"os"
 	"strconv"
 	"time"
 )
@@ -33,6 +35,8 @@ var (
 	ErrMethodNotAllowed = fmt.Errorf("kenall: 405 method not allowed error")
 	// ErrInternalServerError is an error value that will be returned when some error occurs in the kenall service.
 	ErrInternalServerError = fmt.Errorf("kenall: 500 internal server error")
+	// ErrTimeout is an error value that will be returned when the request is timeout.
+	ErrTimeout = func(err error) error { return fmt.Errorf("kenall: request timeout: %w", err) }
 )
 
 type (
@@ -187,12 +191,16 @@ func (cli *Client) sendRequest(req *http.Request, res interface{}) error {
 
 	resp, err := cli.HTTPClient.Do(req)
 	if err != nil {
+		if errors.Is(err, context.DeadlineExceeded) || os.IsTimeout(err) {
+			return ErrTimeout(err)
+		}
+
 		return fmt.Errorf("kenall: failed to do http client with a request for kenall service: %w", err)
 	}
 
 	defer func() {
-		defer resp.Body.Close()
-		io.Copy(ioutil.Discard, resp.Body)
+		_ = resp.Body.Close()
+		_, _ = io.Copy(ioutil.Discard, resp.Body)
 	}()
 
 	switch resp.StatusCode {
diff --git a/kenall_test.go b/kenall_test.go
index 5c90c28..3b3888a 100644
--- a/kenall_test.go
+++ b/kenall_test.go
@@ -71,8 +71,10 @@ func TestNewClient(t *testing.T) {
 func TestClient_GetAddress(t *testing.T) {
 	t.Parallel()
 
+	toctx, cancel := context.WithTimeout(context.Background(), 1*time.Nanosecond)
 	srv := runTestingServer(t)
 	t.Cleanup(func() {
+		cancel()
 		srv.Close()
 	})
 
@@ -97,6 +99,7 @@ func TestClient_GetAddress(t *testing.T) {
 		"Wrong endpoint":        {endpoint: "", token: "opencollector", ctx: context.Background(), postalCode: "0000000", checkAsError: true, wantError: &url.Error{}, wantJISX0402: ""},
 		"Wrong response":        {endpoint: srv.URL, token: "opencollector", ctx: context.Background(), postalCode: "0000001", checkAsError: true, wantError: &json.MarshalerError{}, wantJISX0402: ""},
 		"Nil context":           {endpoint: srv.URL, token: "opencollector", ctx: nil, postalCode: "0000000", checkAsError: true, wantError: errors.New("net/http: nil Context"), wantJISX0402: ""},
+		"Timeout context":       {endpoint: srv.URL, token: "opencollector", ctx: toctx, postalCode: "1008105", checkAsError: true, wantError: kenall.ErrTimeout(context.DeadlineExceeded), wantJISX0402: ""},
 	}
 
 	for name, c := range cases {
@@ -126,8 +129,10 @@ func TestClient_GetAddress(t *testing.T) {
 func TestClient_GetCity(t *testing.T) {
 	t.Parallel()
 
+	toctx, cancel := context.WithTimeout(context.Background(), 1*time.Nanosecond)
 	srv := runTestingServer(t)
 	t.Cleanup(func() {
+		cancel()
 		srv.Close()
 	})
 
@@ -152,6 +157,7 @@ func TestClient_GetCity(t *testing.T) {
 		"Wrong endpoint":          {endpoint: "", token: "opencollector", ctx: context.Background(), prefectureCode: "00", checkAsError: true, wantError: &url.Error{}, wantJISX0402: ""},
 		"Wrong response":          {endpoint: srv.URL, token: "opencollector", ctx: context.Background(), prefectureCode: "95", checkAsError: true, wantError: &json.MarshalerError{}, wantJISX0402: ""},
 		"Nil context":             {endpoint: srv.URL, token: "opencollector", ctx: nil, prefectureCode: "00", checkAsError: true, wantError: errors.New("net/http: nil Context"), wantJISX0402: ""},
+		"Timeout context":         {endpoint: srv.URL, token: "opencollector", ctx: toctx, prefectureCode: "13", checkAsError: true, wantError: kenall.ErrTimeout(context.DeadlineExceeded), wantJISX0402: ""},
 	}
 
 	for name, c := range cases {