A signal generation circuit (5) generates a pilot signal for communication between a vehicle equipped with a battery device, and a charging cable. The circuit (5) includes a circuit (5A) includes an operational amplifier (OP1) for outputting the pilot signal, a first input unit (501) for supplying a non-inverted input terminal of the amplifier (OP1) with a first or second signal, a second input unit (51) for supplying an inverted input terminal of the amplifier (OP1) with a first or second voltage, and a control unit (500) for controlling each output of the first and second input units (501, 51). Each of the first signal and the first voltage is a zero voltage. The circuit (5A) is configured so that the amplifier (OP1) outputs a zero voltage if the first signal is supplied to the non-inverted input terminal and the first voltage is supplied to the inverted input terminal.
