To precisely measure and control the amount of a cathode gas supplied to a fuel cell, a fuel cell system includes a fuel cell, a first flow passage through which a cathode gas is supplied to the fuel cell, a second flow passage through which a cathode off-gas is discharged from the fuel cell, a bypass flow passage which is bifurcated from the first flow passage and which is connected to the second flow passage, a compressor provided in the first flow passage, a first flowmeter provided in the first flow passage, a flow amount regulation valve provided in the bypass flow passage, a second flowmeter provided in the bypass flow passage, and a controller which controls the flow amount of the cathode gas supplied to the fuel cell, wherein the compressor is arranged on the upstream side of the bypass flow passage, the first flowmeter is arranged on the upstream side of the compressor, the second flowmeter is arranged on the downstream side of the flow amount regulation valve, and the controller controls the flow amount of the cathode gas supplied to the fuel cell based on the flow amount measured by the first flowmeter and the flow amount measured by the second flowmeter.