diff --git a/package.json b/package.json
index b40fe2c..bebe2c9 100644
--- a/package.json
+++ b/package.json
@@ -47,7 +47,7 @@
     "ts-loader": "^3.2.0",
     "tslint": "^5.9.1",
     "typescript": "^2.7.2",
-    "webpack": "^3.10.0"
+    "webpack": "^4.39.2"
   },
   "url": "https://github.com/Ikagaka/ukagaka-timer-event-source.js",
   "author": {