password less login to root from a user account

hello friends,
one user is created named "user1"

I login as "user1" . Now when i do "su -" to be root user I have to give password for root .

Is there any way through which we can skip giving the password to root.

i.e.
user1@work:~$ su -
Password: xxxxxx
work:~$

I don't want that password to be asked.

setup sudo..

It will ask for user1's password, or you can setup sudoers file with no password option.

Then you can use:

$ sudo su -