There is provided a fuel cell system. The fuel cell system includes a gas pump that is configured to have a rotating body and circulate an exhaust gas discharged from a fuel cell and is provided in a circulation passage configured to connect a discharge passage of the exhaust gas with a fuel gas supply passage. When temperature of the fuel cell is higher than a reference temperature that is a temperature that allows water to be introduced in a supercooled state into the gas pump, the fuel cell system controls the rotation speed of the rotating body of the gas pump to a first rotation speed corresponding to a power generation demand for the fuel cell. When the temperature of the fuel cell is not higher than the reference temperature, the fuel cell system controls the rotation speed of the rotating body of the gas pump to a second rotation speed that is lower than the first rotation speed. The second rotation speed is a rotation speed in a low rotation speed range that allows the water in the supercooled state introduced into the gas pump to be extended between the rotating body and a rotating body-surrounding housing wall. This configuration suppresses freezing of the gas pump in the circulation passage of the exhaust gas at a start-up time of the fuel cell.