Provided is a two-power-supply load driving fuel cell system capable of improving the durability of the fuel cell and the power efficiency of the system. Even if the variation of a load terminal voltage occurs, the variation of the output terminal of an FC can be suppressed due to the high-speed operation of an FCVCU including an SiC-FET, enabling the durability of the FC to be ensured. In addition, since IGBTs are employed in a BATVCU having large average passing power, the power loss of a fuel cell system can be reduced. It is therefore possible to construct a system that takes advantage of the characteristics of the switching elements used in the FCVCU and the BATVCU.