To provide a refrigerant leakage detecting device capable of correctly detecting the leakage of a refrigerant.

A control portion 2 (refrigerant leakage detecting device ) judges the leakage of the refrigerant from a refrigerant circuit 1 when the temperature difference Ta between a maximum temperature and a minimum temperature of an indoor-side heat exchanger 11 within a prescribed judgment time is less than a judgment value Tp. Further the judgment time or the judgment value Tp is corrected according to the number of rotation Z within a prescribed time, of a compressor 15.