A mobile communication system comprising: a plurality of base stations (100, 101, 102, 103), each base station (100, 101, 102, 103) holding a list of neighbor cells including information relating to a Primary Scrambling Code, PSC, assigned to each neighbor cell; a gateway apparatus for performing signaling concerning handover of a mobile station among the base stations (100, 101, 102, 103); wherein the system further comprising: each base station (100, 101, 102, 103) is adapted to: transmit information on the PSC assigned to that base station (100, 101, 102, 103) to the gateway apparatus in a base station registration procedure, and when handover is requested from the mobile station and PSC Confusion occurs based on the list of neighbor cells, transmit a request message to the gateway apparatus for requesting the handover by including notification information to notify the gateway apparatus of the PSC Confusion occurring; and said gateway apparatus is adapted to: hold a first database that stores the PSC from each base station (100, 101, 102, 103) in the base station registration procedure, hold a second database that stores information relating to a history of handover results, whether each handover handled by the gateway apparatus is successful or not, in association with each source base station and each target base station, and when handover is requested with notification of the PSC Confusion, refer to the first database and the second database, and select a target base station based on the history of handover results from the base stations having the PSC relating to the PSC Confusion if an entry relating to the source base station exists in the second database, and select a target base station at random among the base stations having the PSC relating to the PSC Confusion if the entry relating to the source base station does not exist in the second database. each base station (100, 101, 102, 103) is adapted to: transmit information on the PSC assigned to that base station (100, 101, 102, 103) to the gateway apparatus in a base station registration procedure, and when handover is requested from the mobile station and PSC Confusion occurs based on the list of neighbor cells, transmit a request message to the gateway apparatus for requesting the handover by including notification information to notify the gateway apparatus of the PSC Confusion occurring; and transmit information on the PSC assigned to that base station (100, 101, 102, 103) to the gateway apparatus in a base station registration procedure, and when handover is requested from the mobile station and PSC Confusion occurs based on the list of neighbor cells, transmit a request message to the gateway apparatus for requesting the handover by including notification information to notify the gateway apparatus of the PSC Confusion occurring; and said gateway apparatus is adapted to: hold a first database that stores the PSC from each base station (100, 101, 102, 103) in the base station registration procedure, hold a second database that stores information relating to a history of handover results, whether each handover handled by the gateway apparatus is successful or not, in association with each source base station and each target base station, and when handover is requested with notification of the PSC Confusion, refer to the first database and the second database, and select a target base station based on the history of handover results from the base stations having the PSC relating to the PSC Confusion if an entry relating to the source base station exists in the second database, and select a target base station at random among the base stations having the PSC relating to the PSC Confusion if the entry relating to the source base station does not exist in the second database. hold a first database that stores the PSC from each base station (100, 101, 102, 103) in the base station registration procedure, hold a second database that stores information relating to a history of handover results, whether each handover handled by the gateway apparatus is successful or not, in association with each source base station and each target base station, and when handover is requested with notification of the PSC Confusion, refer to the first database and the second database, and select a target base station based on the history of handover results from the base stations having the PSC relating to the PSC Confusion if an entry relating to the source base station exists in the second database, and select a target base station at random among the base stations having the PSC relating to the PSC Confusion if the entry relating to the source base station does not exist in the second database.