A fuel cell system includes: a dilute tank that stores an aqueous solution of liquid fuel and supplies the solution to the anode of a fuel cell; a fuel tank connected to the dilute tank via a first controlling section; a water tank connected to the dilute tank via a second controlling section; and controlling means including a current detector which measures the amount of the fuel consumed by the fuel cell from the amount of power generation. The controlling means controls the first controlling section based on the measured amount of fuel consumption and further includes correcting means for measuring a component of a gas discharged from the cathode, calculating the amount of the fuel which has crossed over from the anode to the cathode based on the measured component, and correcting the measured amount of fuel consumption based on the calculated amount of fuel crossover.