To effectively charge an auxiliary power source 50 assisting a main power source 100 in accordance with a travel state of a vehicle.

The auxiliary power source 50 as an electric storage device is connected between the main power source 100 and a motor drive circuit 30 in parallel. A power source control part 62 controls boosting voltage of a boosting circuit 40 to make actual charge capacity of the auxiliary power source 50 to be the target charge capacity. The target charge capacity is set to increase as deceleration of the vehicle is larger. When the vehicle is in deceleration, kinetic energy of the vehicle is consumed by brakes. Therefore, excess kinetic energy is actively recovered and used for charging the auxiliary power source 50.