A power supply control apparatus controls supply of power to an accessory device connected to a first battery. The power supply control apparatus includes a power supply controller that switches a power supply state from a first state to a second state. In the first state, power is supplied to the accessory device via a power converter from a second battery that has a charge/discharge efficiency higher than the first battery. In the second state, the power is supplied from the second battery to the accessory device not via the power converter with the first battery disconnected from the accessory device.