The present disclosure proposes a method for supporting a handover by a base station controller in a cellular mobile communication system including a terminal for performing a handover from a serving cell base station to a target cell base station, the method comprising the steps of: determining handover performance of the terminal; checking whether a resource of the same frequency and time slot as a frequency and time slot of a resource in use by the serving cell base station is usable in the target cell base station; and allocating a resource of the same frequency and time slot to the target cell base station, and transmitting a message indicating channel activation of the allocated resource to the target cell base station.