FUEL CELL SYSTEM

The present disclosure provides a fuel cell system that achieves a stable operation of a turbo compressor. The fuel cell system includes: a fuel cell; an air supply flow path; a turbo compressor; a bypass flow path configured to discharges air by branching off from the air supply flow path; a pressure regulating valve; a bypass valve; and a control unit, the pressure regulating valve, and the bypass valve, in which the control unit calculates, from a flow rate of air supplied based on an actual rotation speed of the turbo compressor and a target flow rate of air to the fuel cell, a flow rate of excess air discharged from the bypass flow path, and determines a degree of opening of the bypass valve based on the target flow rate of air and the flow rate of excess air.