A vapor-compression refrigerant cycle system includes a first evaporator in which refrigerant is evaporated, a second evaporator in which refrigerant is evaporated at a pressure lower than that in the first evaporator, and a switching device for switching between a first circulation where the refrigerant is circulated to the first evaporator and a second circulation where the refrigerant is circulated to the second evaporator. When the switching device switches to the second circulation from the first circulation, a refrigerant circulation into the second evaporator is stopped until the refrigerant pressure in the second evaporator becomes equal to or lower than a predetermined pressure. Therefore, the pressure in the second evaporator can be rapidly reduced. Further, when carbon dioxide is used as the refrigerant, the pressure in the second evaporator can be further rapidly reduced.