A location update method in a wireless communication system is disclosed. The method for performing a location update in a mobile station (MS) of the wireless communication system including a femtocell includes receiving a deregistration command (DREG-CMD) message that includes not only a paging group identifier (ID) of a first femtocell base station (BS) in which the MS stays but also a paging group ID of a macro BS including the first femtocell BS, initiating a location update delay timer while the MS moves from the first femtocell area to a second femtocell area having a paging group ID different from that of the first femtocell, and performing location update according to an operation of the location update delay timer.