In a fire alarm system including a plurality of addressable detectors (203A...N) connected to a main circuit (202a,202b) connected to a central receiving unit (201), any alarmed detector is discriminated and indicated in accordance with its address by the receiving unit (201). In this system, each addressable detector is assigned as a group master detector to each of the areas under surveillance and is conected to a plurality of slave detectors (204A...N) within the same area under surveillance which have no addressing function. Each of the addressable detectors (203A...N) includes a current limiting circuit (218) which on receipt of an alarm signal limits the amount of current supplied to the main circuit (202a,202b) to which the addressable detector (203A...N) is connected, and a changeover circuit (Tr1,Tr2) for changing over the limited current value by the current limiting circuit (218) to a lower value in response to an address-­designated control signal supplied form the receiving unit (201) when the number of alarmed detectors exceeds a predetermined number.