nodemonをinstallできません。どのようにしたらインストールできるようになるのでしょうか?

ちなみにnpmのversionは5.6.0です。

hattoriorunoMBP:~ hattoriakitsugu$ npm install nodemon -g
npm WARN checkPermissons Missing write access to /Users/hattoriakitsugu/.npm-global/lib/node_modules/nodemon
npm ERR! path /Users/hattoriakitsugu/.npm-global/lib/node_modules/nodemon
npm ERR! code EACCES
npm ERR! errno -13
npm ERR! syscall access
npm ERR! Error: EACCESS: permission denied, access '/Users/hattoriakitsugu/.npm-global/lib/node_modules/nodemon'
npm ERR!  { Error: EACCESS: permission denied, access '/Users/hattoriakitsugu/.npm-global/lib/node_modules/nodemon'
npm ERR!   stack: 'Error: EACCESS: permission denied, access \'/Users/hattoriakitsugu/.npm-global/lib/node_modules/nodemon\'',
npm ERR!   errno: -13,
npm ERR!   code: 'EACCESS',
npm ERR!   syscall: 'access',
npm ERR!   path: '/Users/hattoriakitsugu/.npm-global/lib/node_modules/nodemon' }
npm ERR!
npm ERR! Please try running this command again as root/Administrator.

npm ERR! A complete log of this run can be found in:
npm ERR!     /Users/hattoriakitsugu/.npm/_logs\2018-05-20T00_03_54_549Z-debug.log

追記

さらに、sudoコマンドを使ってもできませんでした。

hattoriorunoMBP:~ hattoriakitsugu$ sudo npm install nodemon -g
Password:
/Users/hattoriakitsugu/.npm-global/bin/nodemon -> /Users/hattoriakitsugu/.npm-global/lib/node_modules/nodemon/bin/nodemon.js

> nodemon@1.17.4 postinstall /Users/hattoriakitsugu/.npm-global/lib/node_modules/nodemon
> node bin/postinstall || exit 0

Love nodemon? You can now support the project via the open collective:
 > https://opencollective.com/nodemon/donate

+ nodemon@1.17.4
updated 1 package in 7.455s