PURPOSE: To permit the arrangement of a heat sensitive tube without being contacted with a refrigerant tube wound around the periphery of an inner box by a method wherein the title low-temperature case is provided with a first tubular body made of a metal,which is fixed to an inner box so as to ride over the refrigerant tube and provided with legs having the height higher than the outer diameter of the refrigerant tube, a second tubular body made of a resin, whose one end is connected to the first tubular body and whose other end is projected to the outer part of an outer casing, and temperature sensitive elements inserted into both of the tubular bodies.

CONSTITUTION: A temperature sensitive tube 20 for fixing a temperature sensitive element 25 is constituted of a first tubular body 22 made of a metal such as aluminum or the like, which is provided with legs 21 having height higher than the outer diametral of a cooling tube 6 fixed to the outer surface of an inner box 2 so as to ride over a refrigerant tube or a cooling tube 6, and a second tubular body 23, whose one end is communicated with the first tubular body 22 and the other end is projected to the outside of the outer casing 3. In this case, the temperature sensitive element 25 is preferably inserted from the other end side of the second tubular body 23 and the temperature sensitive part 26 is preferably retained in the first tubular body 22.