PURPOSE: To permit the efficient operation of a refrigerating device by a method wherein the operation of a high-stage side compressor is stopped when the detecting value of a detector has become lower than a predetermined value.

CONSTITUTION: The ambient air temperature of a first evaporator 5 or a temperature or a pressure at a place corresponding to the environment of the first evaporator 5 is detected by a first detector 13 and when the detected value of the detector 13 has become lower than a predetermined value, a high-stage side compressor 1 is stopped and a first solenoid valve 3 is closed at the same time. When the pressure of a low-pressure side compressor 10 is increased remarkably and a trouble due to the deterioration of the cooling capacity in a second evaporator 9 is caused in a case when the high-stage side compressor 1 is stopped by only the first detector 13, the high-stage side compressor 1 is stopped by signals from the first detector 13 and a second detector 14. According to this method, the operation of the high-stage side compressor 1, which is not necessary during the operation of the low-stage side compressor 10, can be stopped.