When i transfer my private key file to my new Mac OS X, i got an error message below:-

If you are getting this error then you probably reset the permissions on your hidden .ssh directory in your user folder.

So, the solution for this is, make that file(id_rsa) readable or writable only for the owner with private key. Below is the command

sudo chmod 600 ~/.ssh/id_rsa

After change the permission, my problem is solved.