diff --git a/README.md b/README.md
index 55aedd73..a96136d4 100644
--- a/README.md
+++ b/README.md
@@ -84,6 +84,14 @@ $ npm install
 $ npm run dev
 ```
 
+### How to add new language
+
+1. First, please prepare [translation](https://github.com/h3poteto/whalebird-desktop/blob/master/src/config/locales/fr/translation.json), and [translation missing](https://github.com/h3poteto/whalebird-desktop/blob/master/src/config/locales/fr/translation.missing.json) file for your language.
+2. Next, add your language to constants like [French](https://github.com/h3poteto/whalebird-desktop/blob/master/src/constants/language.js#L10-L13).
+3. Finally, add your language at [here](https://github.com/h3poteto/whalebird-desktop/blob/master/src/renderer/components/Preferences/Language.vue#L37).
+
+If there is something unknown, please refer this pull request: https://github.com/h3poteto/whalebird-desktop/pull/502
+
 ## Release
 ### Binary
 When you build release packages, please use `electron-builder`.