A motor generator control unit controls operation of a motor generator which generates power using a driving force transmitted from an engine. A charge/discharge control unit electrically connects first and second electrical power storage devices and controls charging/discharging of power between the first and second electrical power storage devices in response to an externally supplied control signal. A motor which is electrically connected to the second electrical power storage device is capable of regenerating electric energy and storing the regenerated energy in the second electrical power storage device. A control device supplies a control signal to at least one of the motor generator control unit and the charge/discharge control unit and reduces an electrical power storage target value of at least one of the first and second electrical power storage devices before the motor regenerates energy.