PURPOSE: To suppress varying range of a temperature in a cooling chamber, and to improve the preservation of a material to be cooled by starting the operation of a refrigerating cycle when a door is opened during the stop of the cycle.

CONSTITUTION: When a set temperature (t) is set, the stopping temperature Toff and operating temperature TON of a refrigerating cycle are automatically set. When a detection temperature TS of a temperature detector becomes the temperature TON or higher, a compressor and a motor-driven blower are started to cool in a cooling chamber. When a door 2 is opened during the stop of the cycle, 'is door opened' is judged with a flag '0', 'YES' is processed, and it is altered to flag '1'. 'whether detection temperature TS is stopping temperature Toff or lower' is judged, and 'NO' is processed with TS>Toff. 'whether flag=1?' is judged, 'YES' is obtained, and the cycle is started. Accordingly, when the door is opened, the cycle is operated even during the stop of the cycle to suppress the rise of the temperature in the cooling chamber.