A vehicle power supply apparatus includes first and second power supply systems, first and second switches, first and second switch controllers, a generator motor controller, an engine controller, and an idling stop determination unit. The idling stop determination unit determines whether or not to inhibit an idling stop control on the basis of a current of an first electrical energy accumulator of the first power supply system, a current of a second electrical energy accumulator of the second power supply system, or a voltage of a generator motor of the second power supply system, or any combination thereof, while recognizing a third control signal to be transmitted to the generator motor, a first control signal to be transmitted to the first switch, and a second control signal to be transmitted to the second switch.