PURPOSE: To make it possible to inhibit a rise in a temperature in a defrosting region to the minimum without lowering the cold insulation and cooling functions in a cooling region by keeping either one of the lower and upper cases under a defrosting condition and the other under a cooling condition, and mixing cooled air with defrosting air at the position of an intake port.

CONSTITUTION: During defrosting in an upper region A, the operation of a first cooler 7 is suspended, and the operation of a second cooler 10 is continued, and then a defrosting heater 16 for the first cooler is thrown in. As a result, the cooled air produced by the second cooler 10 forms an air curtain in the lowest stage region B. Since the lowest stage region M is shielded from the upper region A with the lowest shelf 5, an cold insulation and cooling state is formed in the region B. On the other hand, the air curtain formed between a first diffuser 9 and an intake port 13 rises in its temperature since the first cooler is suspended, but the rise in the temperature is lowered by mixing with the cooled air of the air curtain generated in the lowest stage region B at the intake port 13 and a recovery passage 14, which makes it possible to inhibit the effect on the cold insulation and cooling functions in the upper region to the minimum.