PURPOSE: To maintain proper humidity by integrating an outer layer constituted of micro-porous non-woven cloths formed by heat fusion of heat fusion fibers, an intermediate layer including high water absorption fibers and an inner layer constituted of water permeating non-woven cloth consisting of heat fusion bonding fibers connecting the spaces among the fibers.

CONSTITUTION: As a microporous non-woven cloth as an outer layer 12 is constituted of heat fusion fibers, mixture permeability and water permeating properties of the outer layer 12 can be set selectively by changing properly the content, melting temperature and the like of the heat fusion fibers included therein. An intermediate layer 13 is a fiber layer which is turned into a sheet by the conventional process in the state that high water absorption fibers absorbing surplus water from vegetables, fruits and the like only by themselves or in the state that hydrophilic fibers are added therein and manufactured in the given volume. An inner layer 14 is a water permeating fiber layer covering the intermediate layer 13 together with the outer layer 12, and turned into a sheet by the conventional process in the state of including heat fusion bonding fibers and manufactured into the given volume. Respective fiber layers are integrated by overlapping the intermediate layers 13, the outer layer 12 and the inner layer 14 and, for instance, needling the same.