To simplify a cooler and to reduce a running cost by decreasing a peak load applied to the cooler.

The cooler 5 used for cooling an inner space in a refrigerator 1 or the like for holding the space at a low temperature comprises a cooling tube 6 and a cool thermal storage tube 7 disposed near the tube 6. The cooler 5 is positively operated to be cool thermally stored at night or the like in which an operating efficiency of the cooler 5 is low to operate cold gas stored in the tube 7 in the daytime or the like in which the efficiency of the conventional cooler 5 is high, thereby lowering the efficiency of the cooler 5 in the daytime. The peak load applied to the cooler 5 is lowered to realize a simplification of the cooler 5, thereby reducing an initial cost and a running cost.