An alarm notifying device comprises a circuit which performs communications via a communication line, a circuit which detects a signal indicative of an operating condition of a facility to be monitored, and an alarm signal sent therefrom, and a CPU. The alarm notifying device notifies an alarm to the outside when the alarm signal is detected. The alarm notifying device has the function of receiving a mail, the function of analyzing the contents of a text of the received mail, and the function of changing information lying inside the device according to the contents of the text of the received mail.