PURPOSE: To prevent the shortening of the lifetime of an electronic part, etc., due to the temperature rise of the environment of installation by providing a main circuit section and a control circuit section with temperature detecting means respectively and stopping operation when a temperature detected by either one of the detecting means reaches a set value.

CONSTITUTION: The cooling body 4 of a main circuit section 12 composed of a converter 2, an inverter 3, etc., and a control circuit section 5 are provided with temperature detecting means 6, 26 respectively. The detecting means 6, 26 detect the temperatures of the cooling body 4 of the main circuit section 12 and the control circuit section 5 and prevent bringing to the state of heating of the electronic part, etc., of an inverter device 21, and a switch 13 or a switch 23 is opened when the temperature detected by either one of the detecting means 6, 26 reaches a set value and the circuit of the control circuit section 5 is brought to an open state, thus stopping the operation of the inverter device 21.