US Patent 7455920 Fuel cell system

The fuel cell system comprises a fuel cell (1) that has an electrolyte membrane and generates power by using a fuel gas and an oxidizing agent gas; a storage device (51) for water that humidifies the fuel cell; and a controller (100). The controller (100) judges whether the fuel cell (1) can be humidified by using the water of the storage device (51), and limits the operating temperature of the fuel cell (1) to below a limit temperature that is lower than during normal operation in a case where it is judged that the fuel cell (1) cannot be humidified.