Hand over method using mutual authentication in mobile wibro network system and method

A handover method using mutual authentication in a WiBro(Wireless Broadband) network and its system are provided to improve security by providing an effective handover function and mutual authentication function. When requesting handover from an SBS(Serving Base Station)(200) to a TBS(Target BS)(300), an MS(Mobile Station)(100) generates its temporary number and requests a handover from the SBS. According to the handover request of the MS, the SBS transmits a handover request message including a field for storing the temporary number of the MS to the TBS. The TBS transmits a handover response message including fields for the temporary number of the MS ciphered by using an authentication key received from an authentication server connected via a network and a certificate of the TBS to the SBS.