A power supply system for supplying power to a plurality of loads includes a plurality of fuel cells for generating and supplying power to be supplied to the respectively corresponding loads, wherein the fuel cells are provided to correspond to the plurality of loads, a power network for receiving surplus power, which is generated by the fuel cells except power to be supplied to the loads corresponding to the fuel cells, and supplying the surplus power to the loads short of power, wherein the power network is coupled to the plurality of fuel cells, and a control unit for stopping power generation of a first fuel cell among the fuel cells corresponding to a first load among the loads and controlling a second fuel cell among the fuel cells to generate power to be supplied to the first load as the surplus power if an amount of power to be supplied to the first load is less than a predetermined first threshold.