FUEL CELL SYSTEM AND CONTROL METHOD THEREFOR

The purpose of the present invention is to provide: fuel cell system that can further stabilize an operation of the system; and control method thereof. Fuel cell system comprises: fuel cell; a turbocharger; oxidizing gas supply line that supplies, to cathode, oxidizing gas compressed by a compressor; a heat exchanger that heats the oxidizing gas of the oxidizing gas supply line by means of exhaust gas discharged from a turbine, and flows the exhaust gas to combustion exhaust gas line; bypass lines each having one end connected to the upstream side of the heat exchanger in the oxidizing gas supply line and bypassing the oxidizing gas; flow rate regulating valves provided in the bypass lines; and a control unit that controls the flow rate regulating valves on the basis of the ambient air temperature, and controls the bypass flow rate of the oxidizing gas.