PURPOSE: To prevent dew formation by suppressing a rise of warm air at the bottom of a cold storage chamber as generated by a natural convection and a temperature rise near a door of a low temperature chamber to reduce a temperature difference between the inside and outside of the door of the low temperature chamber.

CONSTITUTION: An elastic seal material 12 is mounted almost across the entire width at the lower side of a door 6 of a low temperature chamber 3 provided at an inner upper part of a cold storage chamber 2. A tip curled part of the elastic seal material 12 is made to abut a door rack 8 elastically as provided almost across the entire width of a door 7 of the cold storage chamber provided almost facing it.