diff --git a/service/bot/ws/metrics.go b/service/bot/ws/metrics.go
new file mode 100644
index 000000000..e7418f083
--- /dev/null
+++ b/service/bot/ws/metrics.go
@@ -0,0 +1,27 @@
+package ws
+
+import (
+	"github.com/gofrs/uuid"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+)
+
+var (
+	webSocketReadBytesTotal = promauto.NewCounterVec(prometheus.CounterOpts{
+		Namespace: "traq",
+		Name:      "bot_ws_read_bytes_total",
+	}, []string{"user_id"})
+
+	webSocketWriteBytesTotal = promauto.NewCounterVec(prometheus.CounterOpts{
+		Namespace: "traq",
+		Name:      "bot_ws_write_bytes_total",
+	}, []string{"user_id"})
+)
+
+func incWebSocketReadBytesTotal(userID uuid.UUID, bytes int) {
+	webSocketReadBytesTotal.WithLabelValues(userID.String()).Add(float64(bytes))
+}
+
+func incWebSocketWriteBytesTotal(userID uuid.UUID, bytes int) {
+	webSocketWriteBytesTotal.WithLabelValues(userID.String()).Add(float64(bytes))
+}
diff --git a/service/bot/ws/session.go b/service/bot/ws/session.go
index c6e48d45b..730f59eb7 100644
--- a/service/bot/ws/session.go
+++ b/service/bot/ws/session.go
@@ -52,6 +52,7 @@ func (s *session) ReadLoop() {
 		if err != nil {
 			return
 		}
+		incWebSocketReadBytesTotal(s.userID, len(m))
 
 		if t == websocket.TextMessage {
 			s.commandHandler(string(m))
@@ -80,6 +81,7 @@ func (s *session) WriteLoop() {
 			if err := s.write(msg.t, msg.data); err != nil {
 				return
 			}
+			incWebSocketWriteBytesTotal(s.userID, len(msg.data))
 
 			if msg.t == websocket.CloseMessage {
 				return