PURPOSE: To provide the automatic incoming call system in a mobile object communication system in which an incoming call can be automatically received at the mobile terminal within the specified group which is the closest to an originating caller within an exchange.

CONSTITUTION: When a call processor 9 receives the originating call of a volunteer calling request from a PS 1b, the password as to whether a notified volunteered password is registered or not by referring to a volunteered registration part 7 is confirmed after a confirmation request is performed. When a volunteered registration is performed for the PS 1b, the call processor 9 gives a simultaneous volunteer calling incoming call request to the positional registration area which is the same as the PS 1b. When a PS 1a responds to the calling, whether the volunteer registration is performed for the PS 1a or not is confirmed by referring to a volunteer registration part 6. When the PS 1a is registered, the calling is performed for the PS 1a and the calling sound of the PS 1a is rung.