PURPOSE: To save a handling time for setting an address and to prevent the generation of the erroneous setting of the address by successively sending a polling signal from a minimum address and repeating the same operation signal at the time of reception by a terminal part.

CONSTITUTION: When the power source of a fire receiver B is supplied and a transmission part D1 successively sends the polling signal, all the sensors S1,... Sn store the addresses of their own. When the polling signal Pn+1 reaches the terminal part D2 of the fire receiver B, the transmission part D1 successively sends a polling signal again and all the sensors S1,... Sn successively send back the state signals (the presence/absence signal of fire sensing) of their own to the transmission part D1. When the fire detection part Sd2 of the sensor S2 of a first system senses the fire and the transmission part D1 sends a polling signal P2, the sensor S2 sends a state signal saying 'fire is sensed' back to the transmission part D1. Then, the repeater D of the first system sends fire signal data saying 'the sensor S2 of the first system senses a fire' to a receiver C.