A fuel cell system includes: a fuel cell; an air discharge passage configured to discharge an air exhaust gas from the fuel cell; a back pressure adjusting valve provided in the air discharge passage and configured to adjust pressure of the air exhaust gas; a cooling device configured to cool the fuel cell by carrying out heat exchange using a heat medium; a water reservoir storing water; a high pressure introduction passage connecting an upstream side of the air discharge passage which is more upstream than the back pressure adjusting valve in an air flow direction to the water reservoir; and a sprinkling device configured to sprinkle the water of the water reservoir over the cooling device. The sprinkling device is configured to sprinkle the water of the water reservoir pumped by pressure of the air exhaust gas over the cooling device.