PURPOSE: To prevent the concentration of inquiries at the time of calling time and called time to a controller performing the centralized control of subscriber information on each terminal and to speed up a call connection, in a mobile object communication network.

CONSTITUTION: This exchanging device is provided with an auxiliary subscriber control part 11 controlling the information on a terminal being present within an area in charge and unnecessitates the retrieval to an external subscriber control device 2 as much as possible. By registering subscriber information obtained by retrieving the external subscriber controller 2 in the auxiliary subscriber control part 11, the retrieval to the subscriber controller 2 is eliminated from the next time. In addition, by providing an auxiliary transmission destination control part 12 being used for the retrieval for the specifying of a called side exchanging device at the time of a calling on the exchanging device, the retrieval of the external subscriber controller 2 is eliminated as much as possible. Further, by transmitting and receiving the moving notification and exchanging error notification on a terminal, the contents of the auxiliary control parts 11, 12 are updated.