diff --git a/Casks/firefox-beta-ja.rb b/Casks/firefox-beta-ja.rb
index 87c564a22..30c27f10f 100644
--- a/Casks/firefox-beta-ja.rb
+++ b/Casks/firefox-beta-ja.rb
@@ -1,6 +1,6 @@
 cask :v1 => 'firefox-beta-ja' do
-  version '38.0.5b1'
-  sha256 'e3da6aa7b564b09221b84576884f62be5d079320faba8276030d93ac44b2a229'
+  version '39.0b5'
+  sha256 'a57af5e2a3daf5d9fd51ff51378ac1731fa0e86ff9638a6c539aa7dfd3c16a1a'
 
   url "https://download.mozilla.org/?product=firefox-#{version}-SSL&os=osx&lang=ja-JP-mac"
   homepage 'https://www.mozilla.org/ja/firefox/channel/beta'