diff --git a/adaptors/cmd.go b/adaptors/cmd.go
index 9b09180f..5229c914 100644
--- a/adaptors/cmd.go
+++ b/adaptors/cmd.go
@@ -3,8 +3,8 @@ package adaptors
 import (
 	"context"
 	"fmt"
-	"log"
 
+	"github.com/int128/kubelogin/adaptors/interfaces"
 	"github.com/int128/kubelogin/usecases/interfaces"
 	"github.com/jessevdk/go-flags"
 	"github.com/mitchellh/go-homedir"
@@ -12,7 +12,8 @@ import (
 )
 
 type Cmd struct {
-	Login usecases.Login
+	Login  usecases.Login
+	Logger adaptors.Logger
 }
 
 func (cmd *Cmd) Run(ctx context.Context, args []string, version string) int {
@@ -23,16 +24,16 @@ func (cmd *Cmd) Run(ctx context.Context, args []string, version string) int {
 		version)
 	args, err := parser.ParseArgs(args[1:])
 	if err != nil {
-		log.Printf("Error: %s", err)
+		cmd.Logger.Logf("Error: %s", err)
 		return 1
 	}
 	if len(args) > 0 {
-		log.Printf("Error: too many arguments")
+		cmd.Logger.Logf("Error: too many arguments")
 		return 1
 	}
 	kubeConfig, err := o.ExpandKubeConfig()
 	if err != nil {
-		log.Printf("Error: invalid option: %s", err)
+		cmd.Logger.Logf("Error: invalid option: %s", err)
 		return 1
 	}
 
@@ -43,7 +44,7 @@ func (cmd *Cmd) Run(ctx context.Context, args []string, version string) int {
 		SkipOpenBrowser: o.SkipOpenBrowser,
 	}
 	if err := cmd.Login.Do(ctx, in); err != nil {
-		log.Printf("Error: %s", err)
+		cmd.Logger.Logf("Error: %s", err)
 		return 1
 	}
 	return 0
diff --git a/adaptors/cmd_test.go b/adaptors/cmd_test.go
index f287472d..9c570396 100644
--- a/adaptors/cmd_test.go
+++ b/adaptors/cmd_test.go
@@ -27,7 +27,8 @@ func TestCmd_Run(t *testing.T) {
 			})
 
 		cmd := Cmd{
-			Login: login,
+			Login:  login,
+			Logger: t,
 		}
 		exitCode := cmd.Run(ctx, []string{executable}, version)
 		if exitCode != 0 {
@@ -50,7 +51,8 @@ func TestCmd_Run(t *testing.T) {
 			})
 
 		cmd := Cmd{
-			Login: login,
+			Login:  login,
+			Logger: t,
 		}
 		exitCode := cmd.Run(ctx, []string{executable,
 			"--listen-port", "10080",
@@ -66,7 +68,8 @@ func TestCmd_Run(t *testing.T) {
 		ctrl := gomock.NewController(t)
 		defer ctrl.Finish()
 		cmd := Cmd{
-			Login: mock_usecases.NewMockLogin(ctrl),
+			Login:  mock_usecases.NewMockLogin(ctrl),
+			Logger: t,
 		}
 		exitCode := cmd.Run(context.TODO(), []string{executable, "some"}, version)
 		if exitCode != 1 {
diff --git a/adaptors/interfaces/adaptors.go b/adaptors/interfaces/adaptors.go
index d867a6fa..a406a911 100644
--- a/adaptors/interfaces/adaptors.go
+++ b/adaptors/interfaces/adaptors.go
@@ -52,3 +52,7 @@ type OIDCAuthenticateOut struct {
 	IDToken         string
 	RefreshToken    string
 }
+
+type Logger interface {
+	Logf(format string, v ...interface{})
+}
diff --git a/adaptors/logger.go b/adaptors/logger.go
new file mode 100644
index 00000000..dc0db4f7
--- /dev/null
+++ b/adaptors/logger.go
@@ -0,0 +1,9 @@
+package adaptors
+
+import "log"
+
+type Logger struct{}
+
+func (*Logger) Logf(format string, v ...interface{}) {
+	log.Printf(format, v...)
+}
diff --git a/di/di.go b/di/di.go
index 874eb87d..7ea2f778 100644
--- a/di/di.go
+++ b/di/di.go
@@ -14,6 +14,7 @@ func Invoke(f func(cmd adaptorsInterfaces.Cmd)) error {
 			KubeConfig: &adaptors.KubeConfig{},
 			HTTP:       &adaptors.HTTP{},
 			OIDC:       &adaptors.OIDC{},
+			Logger:     &adaptors.Logger{},
 		},
 	})
 	return nil
diff --git a/usecases/login.go b/usecases/login.go
index fb40bff5..3df16d1d 100644
--- a/usecases/login.go
+++ b/usecases/login.go
@@ -2,7 +2,6 @@ package usecases
 
 import (
 	"context"
-	"log"
 
 	"github.com/int128/kubelogin/adaptors/interfaces"
 	"github.com/int128/kubelogin/kubeconfig"
@@ -21,6 +20,7 @@ type Login struct {
 	KubeConfig adaptors.KubeConfig
 	HTTP       adaptors.HTTP
 	OIDC       adaptors.OIDC
+	Logger     adaptors.Logger
 }
 
 func (u *Login) Do(ctx context.Context, in usecases.LoginIn) error {
@@ -29,10 +29,10 @@ func (u *Login) Do(ctx context.Context, in usecases.LoginIn) error {
 		return errors.Wrapf(err, "could not read the kubeconfig")
 	}
 
-	log.Printf("Using current-context: %s", cfg.CurrentContext)
+	u.Logger.Logf("Using current-context: %s", cfg.CurrentContext)
 	authProvider, err := kubeconfig.FindOIDCAuthProvider(cfg)
 	if err != nil {
-		log.Printf(oidcConfigErrorMessage, cfg.CurrentContext)
+		u.Logger.Logf(oidcConfigErrorMessage, cfg.CurrentContext)
 		return errors.Wrapf(err, "could not find an oidc auth-provider in the kubeconfig")
 	}
 
@@ -40,16 +40,16 @@ func (u *Login) Do(ctx context.Context, in usecases.LoginIn) error {
 	clientConfig.SetSkipTLSVerify(in.SkipTLSVerify)
 	if authProvider.IDPCertificateAuthority() != "" {
 		filename := authProvider.IDPCertificateAuthority()
-		log.Printf("Using the certificate %s", filename)
+		u.Logger.Logf("Using the certificate %s", filename)
 		if err := clientConfig.AddCertificateFromFile(filename); err != nil {
-			log.Printf("Skip the certificate %s: %s", filename, err)
+			u.Logger.Logf("Skip the certificate %s: %s", filename, err)
 		}
 	}
 	if authProvider.IDPCertificateAuthorityData() != "" {
 		encoded := authProvider.IDPCertificateAuthorityData()
-		log.Printf("Using certificate of idp-certificate-authority-data")
+		u.Logger.Logf("Using certificate of idp-certificate-authority-data")
 		if err := clientConfig.AddEncodedCertificate(encoded); err != nil {
-			log.Printf("Skip the certificate of idp-certificate-authority-data: %s", err)
+			u.Logger.Logf("Skip the certificate of idp-certificate-authority-data: %s", err)
 		}
 	}
 	hc, err := u.HTTP.NewClient(clientConfig)
@@ -70,12 +70,12 @@ func (u *Login) Do(ctx context.Context, in usecases.LoginIn) error {
 		return errors.Wrapf(err, "could not get token from OIDC provider")
 	}
 
-	log.Printf("Got a token for subject=%s", out.VerifiedIDToken.Subject)
+	u.Logger.Logf("Got a token for subject=%s", out.VerifiedIDToken.Subject)
 	authProvider.SetIDToken(out.IDToken)
 	authProvider.SetRefreshToken(out.RefreshToken)
 	if err := u.KubeConfig.WriteToFile(cfg, in.KubeConfig); err != nil {
 		return errors.Wrapf(err, "could not update the kubeconfig")
 	}
-	log.Printf("Updated %s", in.KubeConfig)
+	u.Logger.Logf("Updated %s", in.KubeConfig)
 	return nil
 }
diff --git a/usecases/login_test.go b/usecases/login_test.go
index 26b98014..0871cb0a 100644
--- a/usecases/login_test.go
+++ b/usecases/login_test.go
@@ -102,6 +102,7 @@ func TestLogin_Do(t *testing.T) {
 			KubeConfig: newMockKubeConfig(ctrl, inConfig, outConfig),
 			HTTP:       newMockHTTP(ctrl, httpClientConfig),
 			OIDC:       mockOIDC,
+			Logger:     t,
 		}
 		if err := u.Do(ctx, usecases.LoginIn{
 			KubeConfig: "/path/to/kubeconfig",
@@ -143,6 +144,7 @@ func TestLogin_Do(t *testing.T) {
 			KubeConfig: newMockKubeConfig(ctrl, inConfig, outConfig),
 			HTTP:       newMockHTTP(ctrl, httpClientConfig),
 			OIDC:       mockOIDC,
+			Logger:     t,
 		}
 		if err := u.Do(ctx, usecases.LoginIn{
 			KubeConfig:    "/path/to/kubeconfig",
@@ -186,6 +188,7 @@ func TestLogin_Do(t *testing.T) {
 			KubeConfig: newMockKubeConfig(ctrl, inConfig, outConfig),
 			HTTP:       newMockHTTP(ctrl, httpClientConfig),
 			OIDC:       mockOIDC,
+			Logger:     t,
 		}
 		if err := u.Do(ctx, usecases.LoginIn{
 			KubeConfig:      "/path/to/kubeconfig",
@@ -229,6 +232,7 @@ func TestLogin_Do(t *testing.T) {
 			KubeConfig: newMockKubeConfig(ctrl, inConfig, outConfig),
 			HTTP:       newMockHTTP(ctrl, httpClientConfig),
 			OIDC:       mockOIDC,
+			Logger:     t,
 		}
 		if err := u.Do(ctx, usecases.LoginIn{
 			KubeConfig: "/path/to/kubeconfig",
@@ -273,6 +277,7 @@ func TestLogin_Do(t *testing.T) {
 			KubeConfig: newMockKubeConfig(ctrl, inConfig, outConfig),
 			HTTP:       newMockHTTP(ctrl, httpClientConfig),
 			OIDC:       mockOIDC,
+			Logger:     t,
 		}
 		if err := u.Do(ctx, usecases.LoginIn{
 			KubeConfig: "/path/to/kubeconfig",
@@ -318,6 +323,7 @@ func TestLogin_Do(t *testing.T) {
 			KubeConfig: newMockKubeConfig(ctrl, inConfig, outConfig),
 			HTTP:       newMockHTTP(ctrl, httpClientConfig),
 			OIDC:       mockOIDC,
+			Logger:     t,
 		}
 		if err := u.Do(ctx, usecases.LoginIn{
 			KubeConfig: "/path/to/kubeconfig",
@@ -362,6 +368,7 @@ func TestLogin_Do(t *testing.T) {
 			KubeConfig: newMockKubeConfig(ctrl, inConfig, outConfig),
 			HTTP:       newMockHTTP(ctrl, httpClientConfig),
 			OIDC:       mockOIDC,
+			Logger:     t,
 		}
 		if err := u.Do(ctx, usecases.LoginIn{
 			KubeConfig: "/path/to/kubeconfig",
@@ -407,6 +414,7 @@ func TestLogin_Do(t *testing.T) {
 			KubeConfig: newMockKubeConfig(ctrl, inConfig, outConfig),
 			HTTP:       newMockHTTP(ctrl, httpClientConfig),
 			OIDC:       mockOIDC,
+			Logger:     t,
 		}
 		if err := u.Do(ctx, usecases.LoginIn{
 			KubeConfig: "/path/to/kubeconfig",