To obtain a polyvinyl alcohol compsn. which has improved water and moisture resistance high enough to maintain high gas barrier properties even in a high humidity environment by crosslinking a polyvinyl alcohol resin through an ion bond of a metal atom.

A metal compd. in an amt. of 500 to 5000ppm is added to and dry blended with a polyvinyl alcohol resin, and the blend is then melt extruded to conduct a reaction, thereby neutralizing 50 to 95% of carboxyl groups contained in the polyvinyl alcohol resin to obtain a resin compsn. with the polyvinyl alcohol resin being crosslinked through an ion bond of the metal atom. This compsn. is laminated by melt extrusion onto a substrate film to obtain a packaging material. Alternatively, the resin compsn. may be dissolved in a solvent to prepare a coating compsn. followed by coating or impregnation of a substrate film, paper, nonwoven fabric or the like with the coating compsn. to obtain a packaging material.