In a load driving arrangement, electric power is supplied from an auxiliary battery to a main power supply when the power stored by charging in the main power supply is scarce at the startup of the system. The power is supplied to the main power supply by closing relays to connect the auxiliary battery to the neutral point of an auxiliary motor, operating a switching transistor of a bottom arm of an auxiliary-related inverter based on a command from a control circuit, stepping up the voltage from the auxiliary battery by using a coil of the auxiliary motor as a reactor, and supplying the step-up voltage to the main power supply thereby charging the main power supply. At this time, a drive-related inverter and a DC/DC converter are stopped. When the main power supply is charged to a sufficient degree, the relays are opened to drive each load. Accordingly, the load driving arrangement achieves the function of charging the main power supply at low cost when the power stored therein is scarce at the system startup.