A wireless base station connected together with another base station to a superior apparatus, comprises, a forwarding controller to forward data received from the superior apparatus to the mobile station in a case of receiving none of a handover request message from the mobile station connected to the wireless base station, and to forward a part or the whole of the data received from the superior apparatus to the another wireless base station after receiving the handover request message from the mobile station, and a notifying unit to notify the another wireless base station of information used for the another wireless base station determining a reception allowable period of the data forwarded from the wireless-base station.