PURPOSE: To generate a warning tone of a safety equipment by means of an interphone system by interrupting a warning tone output built in the safety equipment to an electric signal transmitting means such as a speaker or a buzzer of the interphone set having a master set and devices to be called.

CONSTITUTION: Suppose that a bath warning tone release switch 82 is connected to the downstream of a bath relay switch 81 and the water level of a bath reaches a prescribed value or over, a bath sensor 21 gives an output to a bath control circuit 24, the circuit 24 activates the connection of the switch 81 to an oscillator 71 so as to raise a warning tone from a speaker 76 and the warning tone oscillated by the oscillator 71 is generated from the master set 9A and the device 9B to be called of the interphone system 9 via a voltage-frequency converting circuit 74, an amplification and control circuit 91 and a coupling transformer 92. Warning devices 3∼7 such as burglar-proof, leakage of gas and fire are activated similarly.