WATERPROOF FILM， BACK SHEET FOR DISPOSABLE DIAPER， EXCRETION DISPOSAL BAG AND METHOD FOR PRODUCING WATERPROOF FILM

PROBLEM TO BE SOLVED: To provide an environmental response type waterproof film which is excellent in waterproofness in usage and exhibits excellent easy collapsibility. SOLUTION: A waterproof film 1 includes a waterproof layer 10 containing a nanofiber of polysaccharide， in which the nanofiber of the polysaccharide contains amphiphilic polysaccharide or contains modified polysaccharide where at least a part is chemically modified. The waterproof layer preferably further contains a hydrophobizing agent. The polysaccharide is preferably derived from biomass. The polysaccharide is preferably at least one selected from the group consisting of cellulose， chitin and chitosan. A resin layer containing a biodegradable resin as a main component is preferably provided on at least one side of the waterproof layer. SELECTED DRAWING: Figure 1