A fuel cell system includes: a fuel cell stack; a coolant circulation path through which coolant for cooling the fuel cell stack flows; a cathode gas supply flow path that is connected to an inlet of the fuel cell stack, and in which a compressor that supplies cathode gas to the fuel cell stack is arranged; an intercooler that is arranged between an outlet of the compressor and the inlet of the fuel cell stack in the cathode gas supply flow path, is connected to the coolant circulation path, and cools cathode gas discharged from the compressor with use of the coolant; and a regulating valve that is arranged in the cathode gas supply flow path, and regulates a pressure between the outlet of the compressor and the inlet of the fuel cell stack when the fuel cell stack is being started at low temperature.