It is judged whether the abnormal current is due to the electric leakage or not by a detection step detecting the abnormal current by the leakage current detection board and comparing a threshold value of predetermined items stored in a storing unit and actual values corresponding to the items at the time of when a compressor is stopped by detecting the abnormal current in the detection step. Specifically, the abnormal current is recognized as the electric leakage to be displayed on a display unit when at least one of the operating time at the time of detecting the abnormal current, the inner pressure of a motor, and a discharge pipe temperature is lower than the corresponding threshold value.