A communication system includes a mobile terminal; a management device that manage a position of the mobile terminal; a first base station that creates a first cell area and retains management information for managing a mobile terminal in the first cell area; a gateway, arranged between the first base station and the management device, that retains management information for managing a mobile terminal in the first cell area; and a second base station that creates a second cell area. In a case where the management entity of the mobile terminal is changed from the first base station to the second base station, the first base station updates management information, included in its retaining management information, associated with the relevant mobile terminal, and transmits to the gateway a command to update management information associated with the relevant mobile terminal.