Windows 7: Can I restrict access to the file only to one user?

Can I restrict access to the file only to one user (with administrator permission)? Even if another user has administrator permission.

ps it is about system file Windows\System32\drivers\etc\hosts if this is important.

Of course. But anyone part of the Administrators group can just take ownership and alter the permissions. Thus you shouldn't give people administrative power unless its absolutely necessary.

The hosts file is a critical one, I don't think you should restrict access to it, not at least without consequences, as it controls part of the name resolution system. It's by default read-only for every user and read-write for admins only, which should suffice to warrant security.
Why would you want to prevent access to it? It doesn't contains any kind of sensitive information.

Also, you can't prevent administrators from having complete control of the system, that's the purpose of those kind of accounts. Denying permissions on them will stop them, but they can always give access back to themselves, making it a useless "protection".

Any attempt to restrict what an admin account can do is an exercise in futility. All admin accounts are equal. The one you are using is in no way superior to any other. The built in Administrator account is a little different but not relevant to this situation. Any restrictions you might put in place can be undone by any other admin account. This is by design.

You shouldn't be changing permissions on system files unless you really understand what you are doing. This is a lot more complicated that it appears.