diff --git a/tool/merger.rb b/tool/merger.rb
index 9449938332..45880e0128 100755
--- a/tool/merger.rb
+++ b/tool/merger.rb
@@ -13,28 +13,28 @@ ENV['LC_ALL'] = 'C'
 
 def help
   puts <<-end
-simple backport
+\e[1msimple backport\e[0m
   ruby #$0 1234
 
-range backport
+\e[1mrange backport\e[0m
   ruby #$0 1234:5678
 
-backport from other branch
+\e[1mbackport from other branch\e[0m
   ruby #$0 17502 mvm
 
-revision increment
+\e[1mrevision increment\e[0m
   ruby #$0 revisionup
 
-tagging major release
+\e[1mtagging major release\e[0m
   ruby #$0 tag 2.2.0
 
-tagging patch release (about 2.1.0 or later, it means X.Y.Z (Z > 0) release)
+\e[1mtagging patch release\e[0m (about 2.1.0 or later, it means X.Y.Z (Z > 0) release)
   ruby #$0 tag
 
-tagging preview/RC
+\e[1mtagging preview/RC\e[0m
   ruby #$0 tag 2.2.0-preview1
 
-* all operations shall be applied to the working directory.
+\e[33;1m* all operations shall be applied to the working directory.\e[0m
 end
 end