A fuel cell system includes: a fuel cell stack; a centrifugal compressor that compresses and supplies the oxidant gas to the fuel cell stack; a regulating valve that controls pressure at an outlet of the compressor; and a control unit that controls the compressor and the regulating valve, wherein the control unit determines a rotation speed of the compressor and an open degree of the regulating valve based on a target air flow rate corresponding to a current value instructed to the fuel cell stack, actuates the compressor based on the determined rotation speed, and actuates the regulating valve based on the determined open degree. The control unit executes feedback control to reduce the difference between an actual air flow rate and a target air flow rate by changing the open degree of the regulating valve while maintaining the rotation speed of the compressor.