diff --git a/example_test.go b/example_test.go
index 12cf225..b5551d5 100644
--- a/example_test.go
+++ b/example_test.go
@@ -139,7 +139,7 @@ func ExampleSetVersion() {
 	fmt.Println(string(bytes))
 
 	// Output:
-	// {"severity":"DEBUG","caller":"zl/zl.go:85","message":"INIT_LOGGER","version":"v1.0.0","console":"Severity: DEBUG, Output: ConsoleAndFile, File: ./log/example-set-version_v1.0.0.jsonl"}
+	// {"severity":"DEBUG","caller":"zl/zl.go:86","message":"INIT_LOGGER","version":"v1.0.0","console":"Severity: DEBUG, Output: ConsoleAndFile, File: ./log/example-set-version_v1.0.0.jsonl"}
 	// {"severity":"INFO","caller":"https://github.com/nkmr-jp/zl/blob/v1.0.0/example_test.go#L135","message":"INFO_MESSAGE","version":"v1.0.0","detail":"detail info xxxxxxxxxxxxxxxxx"}
 	// {"severity":"WARN","caller":"https://github.com/nkmr-jp/zl/blob/v1.0.0/example_test.go#L136","message":"WARN_MESSAGE","version":"v1.0.0","detail":"detail info xxxxxxxxxxxxxxxxx"}
 
@@ -270,6 +270,24 @@ func ExampleSetOmitKeys() {
 	// {"function":"github.com/nkmr-jp/zl_test.ExampleSetOmitKeys"}
 }
 
+func ExampleSetFieldKey() {
+	setupForExampleTest()
+
+	zl.SetOutputByString("Console")
+	zl.SetStdout()
+	zl.SetOmitKeys(
+		zl.LevelKey, zl.LoggerKey, zl.TimeKey,
+		zl.CallerKey, zl.VersionKey, zl.HostnameKey, zl.StacktraceKey, zl.PIDKey,
+	)
+	zl.SetFieldKey(zl.MessageKey, "msg")
+	zl.SetFieldKey(zl.FunctionKey, "fn")
+	zl.Init()
+	zl.Info("INFO_MESSAGE")
+
+	// Output:
+	// {"fn":"github.com/nkmr-jp/zl_test.ExampleSetFieldKey","msg":"INFO_MESSAGE"}
+}
+
 func ExampleError() {
 	setupForExampleTest()
 
diff --git a/options.go b/options.go
index 7426466..18e7330 100644
--- a/options.go
+++ b/options.go
@@ -186,6 +186,14 @@ func SetOmitKeys(key ...Key) {
 	omitKeys = key
 }
 
+// SetFieldKey is changes the key of the default field.
+func SetFieldKey(key Key, val string) {
+	if key == "" || val == "" {
+		return
+	}
+	fieldKeys[key] = val
+}
+
 // SetStdout is changes the console log output from stderr to stdout.
 func SetStdout() {
 	isStdOut = true
diff --git a/options_test.go b/options_test.go
index a2018ec..733eb8c 100644
--- a/options_test.go
+++ b/options_test.go
@@ -67,8 +67,23 @@ func TestSetLevelByString(t *testing.T) {
 	}
 }
 
-func TestSetSeparator(t *testing.T) {
+func TestSetFieldKey(t *testing.T) {
+	SetFieldKey(FunctionKey, "func")
+	SetFieldKey(StacktraceKey, "stack_trace")
+	SetFieldKey(CallerKey, "")
+	SetFieldKey("", "abc")
+	assert.Equal(t,
+		map[Key]string{
+			FunctionKey:   "func",
+			StacktraceKey: "stack_trace",
+		},
+		fieldKeys,
+	)
 	ResetGlobalLoggerSettings()
+}
+
+func TestSetSeparator(t *testing.T) {
 	SetSeparator(":")
 	assert.Equal(t, ":", separator)
+	ResetGlobalLoggerSettings()
 }
diff --git a/zl.go b/zl.go
index d610c7a..c2a221c 100644
--- a/zl.go
+++ b/zl.go
@@ -36,6 +36,7 @@ var (
 	callerEncoder  zapcore.CallerEncoder
 	consoleFields  = []string{consoleFieldDefault}
 	omitKeys       []Key
+	fieldKeys      = make(map[Key]string)
 	isStdOut       bool
 	separator      = " "
 	pid            int
@@ -88,13 +89,13 @@ func Init() {
 
 func newEncoderConfig() *zapcore.EncoderConfig {
 	enc := zapcore.EncoderConfig{
-		MessageKey:     string(MessageKey),
-		LevelKey:       string(LevelKey),
-		TimeKey:        string(TimeKey),
-		NameKey:        string(LoggerKey),
-		CallerKey:      string(CallerKey),
-		FunctionKey:    string(FunctionKey),
-		StacktraceKey:  string(StacktraceKey),
+		MessageKey:     fieldKey(MessageKey),
+		LevelKey:       fieldKey(LevelKey),
+		TimeKey:        fieldKey(TimeKey),
+		NameKey:        fieldKey(LoggerKey),
+		CallerKey:      fieldKey(CallerKey),
+		FunctionKey:    fieldKey(FunctionKey),
+		StacktraceKey:  fieldKey(StacktraceKey),
 		EncodeLevel:    zapcore.CapitalLevelEncoder,
 		EncodeTime:     zapcore.RFC3339NanoTimeEncoder,
 		EncodeDuration: zapcore.StringDurationEncoder,
@@ -104,6 +105,14 @@ func newEncoderConfig() *zapcore.EncoderConfig {
 	return &enc
 }
 
+func fieldKey(key Key) string {
+	value, ok := fieldKeys[key]
+	if !ok {
+		return string(key)
+	}
+	return value
+}
+
 // See https://pkg.go.dev/go.uber.org/zap
 func newLogger(enc *zapcore.EncoderConfig) *zap.Logger {
 	core := zapcore.NewCore(
@@ -270,6 +279,7 @@ func ResetGlobalLoggerSettings() {
 	callerEncoder = nil
 	consoleFields = []string{consoleFieldDefault}
 	omitKeys = nil
+	fieldKeys = make(map[Key]string)
 	isStdOut = false
 	separator = " "
 	fileName = ""