PURPOSE: To provide a circuit for controlling the output of car audio equipment which can suppress the current consumption of car audio equipment to the minimum when a vehicle key switch is at the accessory position and can prevent the quick exhaustion of a battery.

CONSTITUTION: Car audio equipment 10 which is supplied with a power supply voltage from a battery 1 through the accessory terminal of a vehicle key switch 3 is provided with a control means which detects the presence/absence of a voltage signal 8 from the ignition terminal of the switch 3 and controls the output of the equipment 10 so that the output can be reduced by a prescribed level based on the detecting signal.