PURPOSE: To minimize the danger of a present person and to increase the possibility of arresting an intruder by receiving function signals from a master alarming device in a central control station and discriminating which of remote detectors is operated.

CONSTITUTION: The master alarming device 10 positioned in a guard area is provided and the master alarming device 10 is provided with a means for performing communication with the central control station 11 through a telephone line. Also, the plural remote detectors 13 to be connected to the master alarming device 10 at the time of an operation are provided in difference zones inside a security area. Thus, when the master alarming device 10 is operated by the operation of the remote detector 13, the central control station 11 becomes operatable so as to discriminate which of remote detectors 13 is operated. Thus, the danger of the present person is minimized and the possibility of arresting the intruder is increased.