Modified polyvinyl alcohol and a manufacturing method thereof

A monomer unit represented by the following formula (1) contains 0.1 to 10 mol%, and denatured polyvinyl alcohol polymerization degree is more than 2000. Thus, excellent in solubility in water, foaming of the aqueous solution is small, modified polyvinyl alcohol is excellent in film strength and gas barrier properties under high humidity is provided. [In Formula (1), ]