In order to more rapidly warm up a battery device in a power supply equipped with a fuel cell and a battery device, a fuel-cell-mounted vehicle driving system for driving and controlling a rotating electric machine installed on a vehicle comprises an inverter connected to the rotating electric machine; a power supply circuit having a battery device, a voltage converter, and a fuel cell; and a power supply control device for controlling the power supply circuit. The power supply control device includes an FC output voltage setting module for setting the output voltage of the fuel cell, an OCV avoidance module for, when an FC output voltage is set, avoiding a voltage around an OCV, a battery warm-up control determination module for determining whether the battery device is under warm-up control or not, and an OCV avoidance release module for, when the battery device is under the warm-up control, releasing the OCV avoidance.