diff --git a/Gemfile.lock b/Gemfile.lock
index 9c686d7..0de6ca7 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -17,7 +17,6 @@ PATH
       settingslogic
       sqlite3
       sucker_punch (~> 1.0.5)
-      uglifier (>= 1.3.0)
 
 GEM
   remote: https://rubygems.org/
@@ -69,7 +68,6 @@ GEM
     domain_name (0.5.18)
       unf (>= 0.0.5, < 1.0.0)
     erubis (2.7.0)
-    execjs (2.1.0)
     factory_girl (4.4.0)
       activesupport (>= 3.0.0)
     factory_girl_rails (4.4.1)
@@ -206,9 +204,6 @@ GEM
       polyglot (>= 0.3.1)
     tzinfo (1.2.1)
       thread_safe (~> 0.1)
-    uglifier (2.5.0)
-      execjs (>= 0.3.0)
-      json (>= 1.8.0)
     unf (0.1.4)
       unf_ext
     unf_ext (0.0.6)
diff --git a/fluentd-ui.gemspec b/fluentd-ui.gemspec
index 781eaf9..1fd3a05 100644
--- a/fluentd-ui.gemspec
+++ b/fluentd-ui.gemspec
@@ -27,7 +27,6 @@ Gem::Specification.new do |spec|
   spec.add_dependency 'addressable'
   spec.add_dependency "font-awesome-rails"
   spec.add_dependency 'sass-rails', '~> 4.0.3'
-  spec.add_dependency 'uglifier', '>= 1.3.0'
   spec.add_dependency "haml-rails", "~> 0.5.3"
   spec.add_dependency 'jquery-rails', "~> 3.1.0"
   spec.add_dependency 'jbuilder', '~> 2.0'