To reduce heat loss and efficiently produce cooling air at desired temperature.

Two cold air generating chambers 30A and 30B can communicate respectively through a plurality of cooling devices, a supply pipeline 23 and a recovery pipeline 21, communicate with each other through a communicating part 44, and supply to the respective cooling devices through the supply pipeline 23 the cooling air which is recovered from the respective cooling devices through the recovery pipeline 21 and cooled by a heat exchanger. One cold air generating chamber 30A alternately and selectively communicates with the supply pipeline 23 and at least one of the cold air generating chambers 30A and 30B communicates with the recovery pipeline 21, and when the cold air generating chamber 30B whose communication with the supply pipeline 23 is interrupted communicates with the recovery pipeline 21, the communicating part 44 is opened.