A mobile terminal and method of notifying an access router of an Internet protocol (IP) address of the mobile terminal in a wireless network are provided where a mobile terminal notifies an access router of an IP address of the mobile terminal, performing duplicate address detection (DAD) with respect to an automatically-configured IP address are performed, and a notification message including the IP address resulting from the performing of the DAD are transmitted to the access router. The access router is notified by using the notification message. The mobile terminal uses the IP address, based on whether there is a response with respect to the notification message transmitted to the access router after the performing of the DAD.