diff --git a/cmd/egress-controller/main.go b/cmd/egress-controller/main.go
index b60709c..83391fd 100644
--- a/cmd/egress-controller/main.go
+++ b/cmd/egress-controller/main.go
@@ -4,24 +4,26 @@ import (
 	"crypto/tls"
 	"flag"
 	"fmt"
+	"log/slog"
 	"os"
 
 	// Import all Kubernetes client auth plugins (e.g. Azure, GCP, OIDC, etc.)
 	// to ensure that exec-entrypoint and run can make use of them.
 	_ "k8s.io/client-go/plugin/pkg/client/auth"
+	"k8s.io/klog/v2"
 
 	"k8s.io/apimachinery/pkg/runtime"
 	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
 	clientgoscheme "k8s.io/client-go/kubernetes/scheme"
 	ctrl "sigs.k8s.io/controller-runtime"
 	"sigs.k8s.io/controller-runtime/pkg/healthz"
-	"sigs.k8s.io/controller-runtime/pkg/log/zap"
 	"sigs.k8s.io/controller-runtime/pkg/metrics/filters"
 	metricsserver "sigs.k8s.io/controller-runtime/pkg/metrics/server"
 	"sigs.k8s.io/controller-runtime/pkg/webhook"
 
 	ponav1beta1 "github.com/cybozu-go/pona/api/v1beta1"
 	"github.com/cybozu-go/pona/internal/controller"
+	"github.com/go-logr/logr"
 	// +kubebuilder:scaffold:imports
 )
 
@@ -65,10 +67,6 @@ func main() {
 	flag.IntVar(&config.FoUPort, "fou-port", 5555, "port number for foo-over-udp tunnels")
 	flag.StringVar(&config.NatGatewayImage, "natgateway-image", "", "default image name for nat-gateway pods")
 
-	opts := zap.Options{
-		Development: true,
-	}
-	opts.BindFlags(flag.CommandLine)
 	flag.Parse()
 
 	if config.NatGatewayImage == "" {
@@ -76,7 +74,11 @@ func main() {
 		os.Exit(1)
 	}
 
-	ctrl.SetLogger(zap.New(zap.UseFlagOptions(&opts)))
+	l := slog.New(slog.NewJSONHandler(os.Stdout, nil))
+	logger := logr.FromSlogHandler(l.Handler())
+	slog.SetDefault(l)
+	klog.SetLogger(logger)
+	ctrl.SetLogger(logger)
 
 	// if the enable-http2 flag is false (the default), http/2 should be disabled
 	// due to its vulnerabilities. More specifically, disabling http/2 will
diff --git a/cmd/nat-gateway/main.go b/cmd/nat-gateway/main.go
index 8f6cd6c..9b6fc26 100644
--- a/cmd/nat-gateway/main.go
+++ b/cmd/nat-gateway/main.go
@@ -4,6 +4,7 @@ import (
 	"crypto/tls"
 	"errors"
 	"flag"
+	"log/slog"
 	"net/netip"
 	"os"
 	"strings"
@@ -11,13 +12,13 @@ import (
 	// Import all Kubernetes client auth plugins (e.g. Azure, GCP, OIDC, etc.)
 	// to ensure that exec-entrypoint and run can make use of them.
 	_ "k8s.io/client-go/plugin/pkg/client/auth"
+	"k8s.io/klog/v2"
 
 	"k8s.io/apimachinery/pkg/runtime"
 	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
 	clientgoscheme "k8s.io/client-go/kubernetes/scheme"
 	ctrl "sigs.k8s.io/controller-runtime"
 	"sigs.k8s.io/controller-runtime/pkg/healthz"
-	"sigs.k8s.io/controller-runtime/pkg/log/zap"
 	"sigs.k8s.io/controller-runtime/pkg/metrics/filters"
 	metricsserver "sigs.k8s.io/controller-runtime/pkg/metrics/server"
 	"sigs.k8s.io/controller-runtime/pkg/webhook"
@@ -26,6 +27,7 @@ import (
 	"github.com/cybozu-go/pona/internal/controller"
 	"github.com/cybozu-go/pona/pkg/nat"
 	"github.com/cybozu-go/pona/pkg/tunnel/fou"
+	"github.com/go-logr/logr"
 	// +kubebuilder:scaffold:imports
 )
 
@@ -67,13 +69,13 @@ func main() {
 		"If set, HTTP/2 will be enabled for the metrics and webhook servers")
 	flag.IntVar(&config.FoUPort, "fou-port", 5555, "port number for foo-over-udp tunnels")
 
-	opts := zap.Options{
-		Development: true,
-	}
-	opts.BindFlags(flag.CommandLine)
 	flag.Parse()
 
-	ctrl.SetLogger(zap.New(zap.UseFlagOptions(&opts)))
+	l := slog.New(slog.NewJSONHandler(os.Stdout, nil))
+	logger := logr.FromSlogHandler(l.Handler())
+	slog.SetDefault(l)
+	klog.SetLogger(logger)
+	ctrl.SetLogger(logger)
 
 	// if the enable-http2 flag is false (the default), http/2 should be disabled
 	// due to its vulnerabilities. More specifically, disabling http/2 will
diff --git a/cmd/ponad/main.go b/cmd/ponad/main.go
index 1752b4c..b674933 100644
--- a/cmd/ponad/main.go
+++ b/cmd/ponad/main.go
@@ -13,6 +13,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
 	clientgoscheme "k8s.io/client-go/kubernetes/scheme"
+	"k8s.io/klog/v2"
 	ctrl "sigs.k8s.io/controller-runtime"
 	"sigs.k8s.io/controller-runtime/pkg/healthz"
 	metricsserver "sigs.k8s.io/controller-runtime/pkg/metrics/server"
@@ -51,9 +52,12 @@ func main() {
 	flag.IntVar(&config.egressPort, "egress-port", 5555, "UDP port number for egress NAT")
 
 	flag.Parse()
-	logger := slog.New(slog.NewJSONHandler(os.Stdout, nil))
-	slog.SetDefault(logger)
-	ctrl.SetLogger(logr.FromSlogHandler(logger.Handler()))
+
+	l := slog.New(slog.NewJSONHandler(os.Stdout, nil))
+	logger := logr.FromSlogHandler(l.Handler())
+	slog.SetDefault(l)
+	klog.SetLogger(logger)
+	ctrl.SetLogger(logger)
 
 	mgr, err := setupManager(config)
 	if err != nil {
diff --git a/go.mod b/go.mod
index 825c794..2675dd2 100644
--- a/go.mod
+++ b/go.mod
@@ -39,7 +39,6 @@ require (
 	github.com/fsnotify/fsnotify v1.7.0 // indirect
 	github.com/go-logr/logr v1.4.1
 	github.com/go-logr/stdr v1.2.2 // indirect
-	github.com/go-logr/zapr v1.3.0 // indirect
 	github.com/go-openapi/jsonpointer v0.19.6 // indirect
 	github.com/go-openapi/jsonreference v0.20.2 // indirect
 	github.com/go-openapi/swag v0.22.3 // indirect
@@ -77,8 +76,6 @@ require (
 	go.opentelemetry.io/otel/sdk v1.19.0 // indirect
 	go.opentelemetry.io/otel/trace v1.19.0 // indirect
 	go.opentelemetry.io/proto/otlp v1.0.0 // indirect
-	go.uber.org/multierr v1.11.0 // indirect
-	go.uber.org/zap v1.26.0 // indirect
 	golang.org/x/exp v0.0.0-20230522175609-2e198f4a06a1 // indirect
 	golang.org/x/net v0.25.0 // indirect
 	golang.org/x/oauth2 v0.20.0 // indirect
@@ -97,7 +94,7 @@ require (
 	k8s.io/apiextensions-apiserver v0.30.1 // indirect
 	k8s.io/apiserver v0.30.1 // indirect
 	k8s.io/component-base v0.30.1 // indirect
-	k8s.io/klog/v2 v2.120.1 // indirect
+	k8s.io/klog/v2 v2.120.1
 	k8s.io/kube-openapi v0.0.0-20240228011516-70dd3763d340 // indirect
 	sigs.k8s.io/apiserver-network-proxy/konnectivity-client v0.29.0 // indirect
 	sigs.k8s.io/json v0.0.0-20221116044647-bc3834ca7abd // indirect
diff --git a/internal/controller/suite_test.go b/internal/controller/suite_test.go
index d527e0d..3b209bb 100644
--- a/internal/controller/suite_test.go
+++ b/internal/controller/suite_test.go
@@ -2,10 +2,13 @@ package controller
 
 import (
 	"fmt"
+	"log/slog"
+	"os"
 	"path/filepath"
 	"runtime"
 	"testing"
 
+	"github.com/go-logr/logr"
 	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
 
@@ -14,7 +17,6 @@ import (
 	"sigs.k8s.io/controller-runtime/pkg/client"
 	"sigs.k8s.io/controller-runtime/pkg/envtest"
 	logf "sigs.k8s.io/controller-runtime/pkg/log"
-	"sigs.k8s.io/controller-runtime/pkg/log/zap"
 
 	ponav1beta1 "github.com/cybozu-go/pona/api/v1beta1"
 	// +kubebuilder:scaffold:imports
@@ -34,7 +36,10 @@ func TestControllers(t *testing.T) {
 }
 
 var _ = BeforeSuite(func() {
-	logf.SetLogger(zap.New(zap.WriteTo(GinkgoWriter), zap.UseDevMode(true)))
+	l := slog.New(slog.NewTextHandler(os.Stdout, nil))
+	logger := logr.FromSlogHandler(l.Handler())
+	slog.SetDefault(l)
+	logf.SetLogger(logger)
 
 	By("bootstrapping test environment")
 	testEnv = &envtest.Environment{