PURPOSE: To eliminate the floating of the bottom of a freezing chamber even if the use of a refrigerator is stopped and the temperature in the refrigerator is raised by forming a duct formed at the partition in an inner box of a duct cover made of a synthetic resin molded form and one side wall face of the partition, and filling foamable heat insulator in a gap formed between the other wall face of the partition and the cover.

CONSTITUTION: A partition 24 made of the bottom 31 of a freezing chamber and the ceiling 32 of the chamber having a chilled gas suction port 33 of a cold storage chamber is provided, a duct 36 is formed in the partition 24 of the ceiling 32, a duct body 34, a duct cover 35, and a defrosting water reservoir 37, and foamable heat insulator 23 is filled in a gap formed between the cover 35 and the bottom 31. Since the requirements of the duct 36 includes the utilization of the ceiling 32, the contraction in the body 34, and reduction in the height of the cover 35, the gap can be formed between the bottom 31 and the cover 35, the insulator is filled in the gap to integrally foam the bottom 31, thereby eliminating the floating of the bottom due to the strong securing strength of the insulator even if the temperature in a refrigerator is raised.