diff --git a/wshandler/wshandler.go b/wshandler/wshandler.go
index 2e56fe1..d2860ea 100644
--- a/wshandler/wshandler.go
+++ b/wshandler/wshandler.go
@@ -188,6 +188,7 @@ type websocketHandlerBase struct {
 type WebsocketHandler struct {
 	WebsocketApiBroker
 	websocketHandlerBase
+	opt *WebsocketHandlerOption
 }
 
 type wsConfig struct {
@@ -205,7 +206,28 @@ func init() {
 	gob.Register([]any{})
 }
 
-func NewWebsocketHandler(consumer session.Consumer, redisUrl string) (*WebsocketHandler, error) {
+type WebsocketHandlerOption struct {
+	ReadBufferSize, WriteBufferSize int
+}
+
+func Option() *WebsocketHandlerOption {
+	return &WebsocketHandlerOption{
+		ReadBufferSize:  0,
+		WriteBufferSize: 0,
+	}
+}
+
+func (opt *WebsocketHandlerOption) SetReadBufferSize(size int) *WebsocketHandlerOption {
+	opt.ReadBufferSize = size
+	return opt
+}
+
+func (opt *WebsocketHandlerOption) SetWriteBufferSize(size int) *WebsocketHandlerOption {
+	opt.WriteBufferSize = size
+	return opt
+}
+
+func NewWebsocketHandler(consumer session.Consumer, redisUrl string, opts ...*WebsocketHandlerOption) (*WebsocketHandler, error) {
 	var config wsConfig
 	if err := gocommon.LoadConfig(&config); err != nil {
 		return nil, err
@@ -240,6 +262,14 @@ func NewWebsocketHandler(consumer session.Consumer, redisUrl string) (*Websocket
 		}
 	}()
 
+	var opt *WebsocketHandlerOption
+	if len(opts) > 0 {
+		// TODO : opts merge
+		opt = opts[0]
+	} else {
+		opt = Option()
+	}
+
 	ws := &WebsocketHandler{
 		websocketHandlerBase: websocketHandlerBase{
 			redisMsgChanName:  fmt.Sprintf("_wsh_msg_%d", redisSync.Options().DB),
@@ -252,6 +282,7 @@ func NewWebsocketHandler(consumer session.Consumer, redisUrl string) (*Websocket
 			sendMsgChan:       sendchan,
 			sessionConsumer:   consumer,
 		},
+		opt: opt,
 	}
 	consumer.RegisterOnSessionInvalidated(ws.onSessionInvalidated)
 	return ws, nil
@@ -665,7 +696,10 @@ func (ws *WebsocketHandler) upgrade_nosession(w http.ResponseWriter, r *http.Req
 		return
 	}
 
-	var upgrader = websocket.Upgrader{} // use default options
+	var upgrader = websocket.Upgrader{
+		ReadBufferSize:  ws.opt.ReadBufferSize,
+		WriteBufferSize: ws.opt.WriteBufferSize,
+	} // use default options
 	conn, err := upgrader.Upgrade(w, r, nil)
 	if err != nil {
 		w.WriteHeader(http.StatusInternalServerError)