An objective of the present invention is to provide a power supply system which enables stabilization of power supply voltages of multiple areas and/or redundancy to be achieved with low costs. A power supply system includes a main battery for providing power and a sub-battery which is separate from the main battery and provides power. The power supply system further includes switching boxes in first to fourth areas as a plurality of power supply areas configured to be supplied with power from the main battery and sub-battery, the switching boxes switching on/off states of power supplies into the first to fourth areas from the main battery and from the sub-battery. Furthermore, the power supply system includes a control section for switching control of the on/off states for the switching boxes.