diff --git a/nuxt.config.ts b/nuxt.config.ts
index 8955d563..bb513850 100644
--- a/nuxt.config.ts
+++ b/nuxt.config.ts
@@ -1,4 +1,5 @@
 import { Configuration } from '@nuxt/types'
+import { Configuration as WebpackConfiguration } from 'webpack'
 import i18n from './nuxt-i18n.config'
 const purgecss = require('@fullhuman/postcss-purgecss')
 const autoprefixer = require('autoprefixer')
@@ -133,6 +134,10 @@ const config: Configuration = {
           whitelistPatterns: [/(col|row)/]
         })
       ]
+    },
+    extend(config: WebpackConfiguration, _) {
+      // default externals option is undefined
+      config.externals = [{ moment: 'moment' }]
     }
     // https://ja.nuxtjs.org/api/configuration-build/#hardsource
     // hardSource: process.env.NODE_ENV === 'development'