PURPOSE: To suppress the frosting of a low-temperature showcase by cooling a storage room by a cold air flow that is subjected to heat exchange cooling using a second evaporator at an inner layer and a third evaporator at an outer layer on the defrosting of the first evaporator and cooling the storage room by a cold air flow that is subjected to heat exchange cooling using the first evaporator at the inner layer and the third evaporator at the outer layer on the defrosting of the second evaporator.

CONSTITUTION: A pressure reduction liquid refrigerant is constantly supplied to two evaporators when a first evaporator 14 is performing a defrosting operation and second and third evaporators 15 and 19 are performing a cooling operation and when the second evaporator is performing a defrosting operation and the first and third evaporators are performing a cooling operation, so that the amount of supply of the pressure reduction liquid refrigerant in a refrigerator becomes nearly constant. Also, since the other evaporator and the third evaporator 19 at an outer layer 7 are performing a cooling operation while either evaporator of the inner layer 6 is performing defrosting, so that an air flow that is forcibly circulated through the inner and outer layers is cooled and touches an opening 2, thus forming a double-layer air curtain by the cold air flow and suppressing the temperature increase in a storage room 9.