A control unit (20) calculates an output required by an inverter (44) from an acquired accelerator opening (step S12), derives output current-output voltage characteristics corresponding to an acquired amount of gas to calculate from the characteristics a point where an energy conversion efficiency is highest and which is determined as an operating point of a fuel cell (36) and calculates an output power of the fuel cell (36) at that operating point (steps S16 to S20), determines an output voltage required by a battery (40) based on the difference between an inverter requirement output and a fuel cell output power and SOC of the battery (40) (step S24), controls a DC/DC converter (38) to regulate an output voltage of the DC/DC converter (38) so that an output voltage of the battery (40) is equal to the determined output voltage (step S28), and controls an inverter (44) so as to let a motor (46) consume a power equivalent to the requirement output (step S30), whereby the fuel cell (36) can be operated at an operating point where an energy conversion efficiency is high.