A method for inter RAT handover is disclosed. The method for inter RAT handover comprises measuring cell quality of WiMAX neighbor cells from a user equipment of E-UTRAN and transmitting the measured result to an origin base station; and if RRC message is received from the origin base station, the RRC message including WiMAX signal, pre-registering with a target WiMAX base station using tunneling based on second layer protocol. Therefore, the user equipment can continue to receive a service with maintaining current service quality even though the user equipment moves to a heterogeneous network. In addition, it is possible to reduce the time required for the user equipment to perform handover to the target base station. Moreover, if there is a failure of a radio link when the user equipment performs handover, it is possible to enable fast recovery.