To simplify a configuration by eliminating signal transmission between a controller and inverter devices and between the inverter devices.

The inverter device each include: an inverter circuit 7 in which a DC voltage at both ends of a smoothing capacitor 4 is converted to an AC voltage of optional magnitude and frequency to supply the converted AC voltage to a motor 12; a regenerative circuit 30 which is connected to the both ends of the smoothing capacitor 4 and composed of a series circuit of a regeneration resistance 5 and a regenerative transistor 6; and a control means which is composed of a detection circuit 8, a calculation part 11, and a drive circuit 9 for turning on the regenerative transistor 6 when the DC voltage exceeds a predetermined value, in order to consume regeneration power from the motor 12 by the regeneration resistance 5. In a control means of each of the inverter devices 2, 13, an on-voltage level of the regenerative transistor 6 of the inverter device is independently varied in accordance with a regenerating operation state of the inverter device.