To provide a cooler having high energy conservation function by suppressing irregularity of a temperature in the cooler, uniform temperature cooling and suppressing an operating rate with high durability in the cooler used for a refrigerator.

A hollow container 3 is disposed on a circumference of the cooler 1 so as to be brought into contact with a refrigerant passage 2, and cool storage material 4 is charged. A temperature regulating heat-sensitive tube 5 is fixed to a surface of the container 3 of the cooler side. When cooling is started, the material 4 in the container 3 is solidified. When a temperature in the cooler 1 is lowered to exceed a designated temperature, the tube 5 senses the temperature to turn on or off the cooling. During cooling-on period, the cooler 1 derives heat. During cooling-off period, the material 4 derives heat by its thermal storage effect. Accordingly, the cooler 1 can be always held therein at a uniform temperature irrespective of turned-on or turned-off state of the cooling.