NOVELTY - The system has two power supply devices for outputting electric power generation voltage (Vfc) and battery voltage (Vb). A control apparatus i.e. electric control unit (ECU) (24) controls on line operation and switch operation of direct current (DC)-DC converters without making the DC-DC converters into a direct link state. The system controls the DC-DC converters according to fluctuation of required output of a load (30) such that one of the DC-DC converters is switched to continuation or direct link state when switching the other converter from the direct link state to the switching state.    USE - Two power-supply-load drive system for use in a FC electric vehicle (claimed) for driving a load with parallelly connected power supply devices e.g. FCs and BATs such as lithium ion secondary batteries. Can also be used for driving a load with a nickel hydride secondary battery and a capacitor.    ADVANTAGE - The system controls the DC-DC converters according to fluctuation of required output of the load such that one of the DC-DC converters is switched to continuation or direct link state when switching the other DC-DC converter from the direct link state to the switching state, so that application of voltage that is not intended to the power supply device, which switches from the direct link state to the switching state is avoided.    DETAILED DESCRIPTION - The power supply devices are fuel cells (FC) (40) and batteries (BAT) (20). The DC-DC converters are FC voltage control units (FCVCU)/step up converters (21) and BATVCU/buck-boost converters (22). An INDEPENDENT CLAIM is also included for a FC electric vehicle.    DESCRIPTION OF DRAWING(S) - The drawing shows a circuit block diagram of a fuel cell electric vehicle with a power-supply-load drive system.'(Drawing includes non-English language text)'    Battery voltage (Vb)    Electric power generation voltage (Vfc)    BATs (20)    Step up converter (21)    Buck-boost converter (22)    ECU (24)    Load (30)    FCs (40)