A fuel cell includes a fuel cell, auxiliaries, a storage battery, an auxiliary power switching unit and a controlling device. The fuel cell is connected to a system power supply. The auxiliaries are coupled to the fuel cell. The auxiliary power switching unit switches power supplies to at least one of the auxiliaries from the storage battery. When the fuel cell device that is not operating starts operation at a time of power failure of the system power supply, the controlling device determines whether or not each of the auxiliaries need power for startup of the fuel cell and prompts the auxiliary power switching unit to supply the power from the storage battery to one or more auxiliaries for which the controlling device has determined a power demand for the startup.