PURPOSE: To increase velocity of air distribution of a cold air flow with which the opening of a storage chamber is covered, to improve cooling efficiency, and to provide a removable guide plate.

CONSTITUTION: Guide plates 13 and 14 having cold air introduction holes 18 and 19 and hoods 21 and 22 are arranged to a cold air discharge port 11 to form discharge passages 15, 16, and 17. A part of cold air is caused to flow in a lower passage from an upper passage, and an air curtain with which the upper surface opening of a storage chamber is covered causes the generation of a cold air flow the speed and a flow rate of which are gradually increased toward an inner flow, and cooling efficiency is increased by suppressing the occurrence of open air rolling-in operation. Further, by locking the hoods 21 and 22 to support pieces 29 and 34 of support members 26 and 31, mounting and demounting of guide plates 13 and 14 are facilitated.