PURPOSE: To eliminate the transmission of an abnormal signal at the time of the installing/withdrawal works of a guarding terminal equipment by sending the abnormal signal of a fire, invasion, etc., to a guarding monitoring center only in a set guarding period.

CONSTITUTION: A guarding period setting part 14 sets a guarding object period, converts the information into a signal and outputs it to a central processing part 12. The guarding period judgment part 16 of the central processing part 12 always judges whether to be in the guarding period or not by signals from the guarding period setting part 14 and a clock 15 and outputs the signal showing to be in the guarding period to an abnormal signal transmission judgment part 17. At the time of receiving the abnormal signal from a sensor operation detection part 11 in the guarding period, the abnormal signal transmission judgment part 17 sends the abnormal signal to a signal sending part 13. Then, the signal is received from the sensor operation detection part 11 in a period excepting for the guarding period, the abnormal signal is not sent to the signal sending part 13, which converts the signal received from the abnormal signal transmission judgment part 17 into a transmittable signal through a communication line (a) and transmits it to the guarding monitoring center.