To prevent unnecessary interruption of an operation at the time when no substantial failure occurs and to stop the operation surely only when. a substantial failure occurs.

This device is equipped with a transformer 50 which detects a current I flowing through an outdoor machine including a compressor 20, a control part 11 which determines whether an abnormal state occurs or not, on the basis of the result of the detection, and a display unit 70 which informs a user of the result of the determination. The control part 11 interrupts the operation of the compressor 20, at least, for a prescribed time when the current I detected by the transformer 50 is larger than an ordinary current value, but smaller than an allowable maximum current value, or switches the operation over to an operation of low power consumption and recovers it thereafter, while it stops the operation of the outdoor machine forcibly when the current is larger than the allowable maximum current value and also informs the user of the abnormal state through the display panel 20.