To provide a suitable method of dealing with short circuit failure of a semiconductor switch element in a regenerative brake circuit which absorbs regenerative power from a load, in an inverter device that supplies the load with power by inverting a voltage, produced by rectifying the AC voltage of an input power supply, into a desired AC voltage.

In an inverter device 20, when a state monitor 17 determines that a semiconductor switch element 22b forming a regenerative brake circuit 22 has fallen into short circuit failure state due to some factor, an abnormal signal indicating the short circuit failure is transmitted to an inverter control circuit 23. Upon receiving the abnormal signal, the inverter control circuit 23 transmits an interruption command to an electromagnetic contactor 21c forming a main capacitor charging circuit 21 and opens the electromagnetic contactor 21c. Consequently, a current flows through a path of a rectifier 11→a charge resistor 21a→a fuse 21b→a regenerative brake circuit 22→the rectifier 11. The fuse 21b is blown off by this current, thus preventing overheat burning of a brake resistor 22a constituting the regenerative brake circuit 22.