[Task] A high-speed driving is possible, a utilization of a power supply having a low voltage is possible, and a regeneration is easy to be carried out.[Means to solve the task] A first buck-boost chopper portion is provided on an output side of a battery 10 to boost a voltage across battery 10 during a drive of a motor, a second buck-boost chopper portion is provided on an output side of the first buck-boost chopper portion to boost the voltage from an inverter portion 20 during a regeneration, inverter portion 20 of a 120-degree conduction current source inverter is provided on the output side of the second buck-boost chopper portion, and a motor 38 is provided on an output side of inverter portion 20.