An example fuel cell comprises: a gas-liquid separator separately storing gas and water; a discharge valve discharging the gas and the water; a control unit controlling the operation of the discharge valve; and a detector detecting a water level of the gas-liquid separator. The control unit is configured to determine an abnormality of the discharge valve based on a change in water level caused by opening and closing of the discharge valve if the water level detected by the detector is equal to or higher than a first threshold.