Provided is a modified polyvinyl alcohol that includes (meth)acrylamide monomer units, each having an ionic group, has a degree of saponification of 50-99.99 mol%, and has a viscosity-average degree of polymerization of 200-5000, said modified polyvinyl alcohol satisfying formulas (1)-(3) below. The modified polyvinyl alcohol obtained in this way in particular has excellent dispersibility in water. (1) 0.8 &le； (MwUV/MwRI) &le； 1.3； (2) 1 &le； (MwUV/MnUV) &le； 7； (3) 0.03 &le； A280 &le； 0.5.本發明為一種改性聚乙烯醇，其係為包含具有離子性基的(甲基)丙烯醯胺單體單元，且皂化度為50~99.99莫耳%，黏度平均聚合度為200~5000之改性聚乙烯醇，並且滿足下述式(1)~(3)。如前述進行而得到的改性聚乙烯醇，其水中分散性尤佳。0.8≦(MwUV/MwRI)≦1.3 (1) 1≦(MwUV/MnUV)≦7 (2) 0.03≦A280≦0.5 (3)
