PURPOSE: To inexpensively and easily set the start/termination of an intrusion monitoring by installing a first ID discrimination device performing the start setting of the invasion monitoring within a room and installing a second ID discrimination device perfoming the termination setting of the invasion monitoring at the common part of a building, in the building where one enters a room just one gets off an elevator.

CONSTITUTION: In a building where an elevator hall is within a tenant room, a card reader 4 is installed in a tenant and the start/termination of an intrusion monitoring is performed by the card reader 5 of a gateway. As for the setting of the start of the intrusion monitoring, when an elevator reaches, the reader head of the card reader 4 installed at each floor is made to read an ID card, and after a prescribed time has passed, the intrusion monitoring is started. As for the setting of the termination of the intrusion monitoring, when the first man of n floor makes the card reader 5 of the gatewary installed at the lobby of the first floor of a building 1 read the ID card, which tenant is discriminated and the intrusion monitoring of the tenant is terminated.