Provided is a system for providing social network service (SNS) and a method for setting relationship between users of mobile terminals. The system may include a reception unit to receive location information on a user terminal allowing the location information to be shared in response to a friend request from the user terminal, a user terminal identification unit to identify at least one other user terminal present within a preset distance based on the location information on the user terminal and allows location information to be shared, a user information transmission unit to identify and send user information on the other user terminal to the user terminal, and a relationship setting unit to set a relationship between users of the user terminal and the other user terminal when the user information on the other user terminal is selected in the user terminal.