PURPOSE: To obtain the subject apparatus having sufficient dehumidifying ability even in the case of low temperature of the open air by arranging a storage box made of a heat transfer panel at a gap inside a heat insulating box, dehumidifying air in the storage box even with the low-temperature open air.

CONSTITUTION: A storage box 4 made of a heat transfer panel is arranged at a gap inside a heat insulating box 1, an evaporator 8 of a cooling unit 5 and a cold air circulating fan 9 are set in a cooling space and a humidity sensor 21 and a temperature sensor 20 are laid in the storage box. A temperature sensor 26 of the open air is fitted. In the case wherein humidity in the storage box is higher than a desired humidity and the temperature of the open air is lower than a given temperature, the low-temperature open air is introduced into the box by an open air sending fan 24 to dehumidify air in the storage box by the open air.