Method for handover between heterogeneous radio access networks

A handover method between heterogeneous radio access networks which efficiently performs hand over between the heterogeneous radio access networks by using a pre-authorization procedure is provided to improve the service quality by performing authentication before a link layer handover procedure. Information about one or more candidate target access networks is obtained besides the access network in which the multimode mobile terminal connects. A pre-authorization require-message is directly or indirectly transmitted to the target access network selected between the candidate target access networks. The pre-authorization result information performed about the pre-authorization request message send is directly or indirectly received from the target access network. A heterogeneous inter-RAT(Radio Access Technology) handover is performed between heterogeneous radio access networks by using pre-authorization result information.