Each of power supply units in a power supply system according to the present invention includes a power supply module, a voltage increase/decrease circuit for increasing the voltage across the power supply module and outputting the increased voltage to a load, and a control circuit. The control circuit calculates the power of the power supply module on the basis of the voltage across the power supply module and current flowing in the power supply module, outputs the power calculation result to a control circuit of another power supply unit, and generates and outputs a control signal to the voltage increase/decrease circuit on the basis of a target output voltage of the voltage increase/decrease circuit, the power calculation result, and a power calculation result obtained from a control circuit of a third power supply unit.