The present invention is characterized by a hybrid car comprising a motor generator mechanically connected with the crank shaft of an internal combustion engine for driving a car wherein the internal combustion engine is started by electric power supplied by a battery and power is generated by rotation from the internal combustion engine to charge the battery, an inverter for controlling the drive and power generation of the motor generator, and a control circuit for controlling the inverter, this hybrid car further characterized in that the motor generator is driven by battery power to start the internal combustion engine, and after the internal combustion engine has started, the battery is charged by the generator mode operation of the motor generator using the power of the internal combustion engine, wherein a step-down chopper circuit is provided between the battery and the inverter, and step-down control is provided to ensure that the power generation voltage will reach the level of the battery charging voltage through the step-down chopper circuit.