A conventional handover method is performed in units of base stations, so that there is a problem in that a large amount of power for handover is consumed and implementation cost is high.Through dedicated protocol message exchanges between a user equipment and a network or between networks, resource availability of candidate networks is checked in advance, a handover target network is selected from among the candidate networks according to a result of checking, and the selected target network is designated as a network to which the user equipment is handed over.