A method of operating a mobile communication terminal for a handover rejection in a portable Internet system and the mobile communication terminal using the same are disclosed. The method includes transmitting a handover request message to a serving base station and receiving a response message corresponding to the handover request message from the serving base station, in which the handover request message requests a handover operation to at least one target base station. The method also includes checking whether the received response message includes contents regarding the handover rejection, extracting at least one of terminal action instruction information and rejection reason information corresponding to the handover rejection from the response message according to a result of the checking step, and executing an action according to the extracted information.