PURPOSE: To prevent deformation of a cold insulator sheet at the time of unequal swelling and icing of the cold insulator sheet at the time of water absorption by providing a shape holding layer for holding the sheet shape of a cold insulator sheet.

CONSTITUTION: A cold insulator is formed of a cold insulator sheet 12, a water- permeable sheet 13 for coating the cold insulator sheet 12, and a shape holding layer 14 for holding the sheet shape of the cold insulator 12. The cold insulator sheet 12 mixes high water-absorptive polymer, namely, powder or fibrous polymer with fibrous pulp and adds bonding agent therewith to mold a sheet shape. A water-permeable sheet 13 preferably uses water permeable spun bonded nonwoven fabric, namely, water permeable nonwoven fabric such as dry nonwoven fabric or wet nonwoven fabric, water-permeable paper and knitting woven fabric, especially 5% modulus is preferably height 5.0kg/5cm wide or more, side 2.0kg/5cm wide or more at the point for holding a shape. The shape holding layer 14, for example, uses water-permeable nonwoven fabric, paper, knitting woven fabric, synthetic resin net formed in approximately the same shape as the cold insulator sheet 12.