Mobile station notifies base station of identification information of base stations searched by searching as a search list, and the base station notifies the mobile station of base stations which are not regarded as prestored neighbor base stations and base stations which are in an unusable base station list, of the base stations in the notified search list, as an NG list. If necessity of handover is increased, the mobile station receiving the notification executes handover to base stations (for example, base station) in the search list other than the base stations included in the NG list.