山口と申します。

rubocop を install したいのですが、実行時にエラーメッセージが出てしまい
対処方法が分からないので、
ご教示お願いします。

[環境]
Windows 7.1 "スタート" -> Ruby-2.4-x64 -> Ruby-2.4 (Administrator) 
console

C:\Users\0000910700>ver
Microsoft Windows [Version 6.1.7601]
C:\Users\0000910700>ruby --version
ruby 2.4.0p0 (2016-12-24 revision 57164) [x64-mswin64_100]
C:\Users\0000910700>gem --version
2.6.12

* gem: gem update --system -r -p http://my_company.proxy.co.jp:10080
で update を実施済

[rubocop install実行時エラー]
C:\Users\0000910700>gem install rubocop -r -p 
http://my_company.proxy.co.jp:10080
Building native extensions.  This could take a while...
ERROR:  Error installing rubocop:
        ERROR: Failed to build gem native extension.

    current directory: C:/PROGRA~1/RUBY-2~1.4-X/lib/ruby/gems/2.4.0/gems
/rainbow-2.2.2/ext
C:/PROGRA~1/RUBY-2~1.4-X/bin/ruby.exe mkrf_conf.rb

current directory: C:/PROGRA~1/RUBY-2~1.4-X/lib/ruby/gems/2.4.0/gems/
rainbow-2.2.2/ext
C:/PROGRA~1/RUBY-2~1.4-X/bin/ruby.exe -rubygems C:/Program Files/Ruby-2.
4-x64/lib/ruby/gems/2.4.0/gems/rake-12.0.0/exe/rake RUBYARCHDIR=C:/
PROGRA~1/RU
BY-2~1.4-X/lib/ruby/gems/2.4.0/extensions/x64-mswin64-100/2.4.0/rainbow-
2.2.2 RUBYLIBDIR=C:/PROGRA~1/RUBY-2~1.4-X/lib/ruby/gems/2.4.0/extensions
/x64-m
swin64-100/2.4.0/rainbow-2.2.2
C:/PROGRA~1/RUBY-2~1.4-X/bin/ruby.exe: No such file or directory -- C:/
Program (LoadError)

rake failed, exit code 1

Gem files will remain installed in C:/PROGRA~1/RUBY-2~1.4-X/lib/ruby/
gems/2.4.0/gems/rainbow-2.2.2 for inspection.
Results logged to C:/PROGRA~1/RUBY-2~1.4-X/lib/ruby/gems/2.4.0/
extensions/x64-mswin64-100/2.4.0/rainbow-2.2.2/gem_make.out