NOVELTY - A fuel cell power generating device is provided with modifier (3), fuel cell (F1), processing unit, storage unit, fuel cell (F2) and supplying unit. The modifier produces reformed gas by reforming a fuel, and the fuel cell (F1) generates electric power. The processing unit processes the exhaust gas discharged from the fuel cell (F1) during generation of electric power, to produce hydrogen-containing gas or hydrogen. The storage unit stores hydrogen generated in the processing unit. The fuel cell (F2) processes hydrogen, to generate electric power.    USE - Fuel cell power generating device.    ADVANTAGE - The fuel cell power generating device is highly reliable, and economically generates electric power using hydrogen-containing gas or hydrogen.    DETAILED DESCRIPTION - A fuel cell power generating device is provided with modifier, fuel cell (F1), processing unit, storage unit, fuel cell (F2) and supplying unit. The modifier produces reformed gas by reforming a fuel, and the fuel cell (F1) generates electric power using the reformed gas. The processing unit processes the exhaust gas discharged from the fuel cell (F1) during generation of electric power, to produce hydrogen-containing gas or hydrogen. The storage unit stores the hydrogen-containing gas or hydrogen generated in the processing unit. The fuel cell (F2) processes the hydrogen-containing gas or hydrogen, to generate electric power. The starting time of fuel cell (F2) is less than the starting time of fuel cell (F1) while supplying hydrogen-containing gas or hydrogen stored in the storage unit. The supply of hydrogen-containing gas or hydrogen stored in the storage unit is controlled by the supplying unit. The fuel cell (F1) is solid oxide fuel cell or molten carbonate-form fuel cell. The fuel cell (F2) is polymer electrolyte fuel cell. An INDEPENDENT CLAIM is included for control method of fuel cell power generating device.    DESCRIPTION OF DRAWING(S) - The drawing shows the block diagram of fuel cell power generating device. (Drawing includes non-English language text)    Desulfurizer (2)    Modifier (3)    Hydrogen reservoir (7)    Polymer electrolyte fuel cell (9)    Fuel electrode (10)