To provide a voltage inverter capable of preventing generation of wasteful energy consumption and upsizing the device, which is caused by a conventional method of absorbing the generated power of a motor by means of a dynamic braking system.

Attaching a regenerative power storage circuit 5 to a DC circuit of a voltage inverter provides a step-down chopper function of storing generated power regenerated from a motor to DC circuit side in an electric double-layer capacitor C through a reactor L with a transistor TR1 turned on and off, and a step-up chopper function of discharging electric power to the DC circuit through the reactor L and a diode D1 from the electric double-layer capacitor C with a transistor TR2 turned on and off if the motor is in a power running condition or the voltage of DC circuit drops.