An alarm device comprising: a reception circuit section adapted to receive event signals from other alarm devices by performing intermittent reception behavior at a predetermined reception cycle; a transmission circuit section adapted to transmit event signals to the other alarm devices for a transmission time whose duration is equal to or longer than the predetermined reception cycle; a sensor section adapted to detect an abnormal condition; an alert section adapted to output an alarm; an abnormal condition monitoring section which is adapted to, upon receiving an abnormal condition detection signal from the sensor section, output an abnormal condition alarm as a linkage source from the alert section and transmit an event signal indicating the abnormal condition to the other alarm devices through the transmission circuit section, and on the other hand, upon receiving an event signal indicating the abnormal condition from one of the other alarm devices, output an abnormal condition alarm as a linkage destination from the alert section; characterised in that the alarm device further comprises: a preliminary abnormal condition detection section adapted to detect a preliminary abnormal condition when the sensor section detects that the probability of an abnormal condition occurring is greater than a predetermined probability; and a preliminary abnormal condition monitoring section which is adapted to, when the preliminary abnormal condition is detected, transmit an event signal indicating the preliminary abnormal condition to the other alarm devices through the transmission circuit section, and on the other hand, upon receiving an event signal indicating the preliminary abnormal condition from one of the other alarm devices, either change the reception cycle of the reception circuit section to a shorter cycle, or change the reception behavior of the reception circuit section to constant reception. a reception circuit section adapted to receive event signals from other alarm devices by performing intermittent reception behavior at a predetermined reception cycle; a transmission circuit section adapted to transmit event signals to the other alarm devices for a transmission time whose duration is equal to or longer than the predetermined reception cycle; a sensor section adapted to detect an abnormal condition; an alert section adapted to output an alarm; an abnormal condition monitoring section which is adapted to, upon receiving an abnormal condition detection signal from the sensor section, output an abnormal condition alarm as a linkage source from the alert section and transmit an event signal indicating the abnormal condition to the other alarm devices through the transmission circuit section, and on the other hand, upon receiving an event signal indicating the abnormal condition from one of the other alarm devices, output an abnormal condition alarm as a linkage destination from the alert section; characterised in that the alarm device further comprises: a preliminary abnormal condition detection section adapted to detect a preliminary abnormal condition when the sensor section detects that the probability of an abnormal condition occurring is greater than a predetermined probability; and a preliminary abnormal condition monitoring section which is adapted to, when the preliminary abnormal condition is detected, transmit an event signal indicating the preliminary abnormal condition to the other alarm devices through the transmission circuit section, and on the other hand, upon receiving an event signal indicating the preliminary abnormal condition from one of the other alarm devices, either change the reception cycle of the reception circuit section to a shorter cycle, or change the reception behavior of the reception circuit section to constant reception. a preliminary abnormal condition detection section adapted to detect a preliminary abnormal condition when the sensor section detects that the probability of an abnormal condition occurring is greater than a predetermined probability; and a preliminary abnormal condition monitoring section which is adapted to, when the preliminary abnormal condition is detected, transmit an event signal indicating the preliminary abnormal condition to the other alarm devices through the transmission circuit section, and on the other hand, upon receiving an event signal indicating the preliminary abnormal condition from one of the other alarm devices, either change the reception cycle of the reception circuit section to a shorter cycle, or change the reception behavior of the reception circuit section to constant reception.