To provide a PVA-based water-soluble film which has excellent mechanical strength and easy solubility in cold water and also exhibits good solubility in aqueous solutions containing salt components in large amounts, especially in aqueous solutions containing a borate, and to provide an individually packaged detergent using the film as packaging materials.

This water-soluble film comprises a composition comprising 100 pts.mass of a polyvinyl alcohol-based resin which is the copolymer of an aliphatic vinyl ester with 0.1 to 20 mol.% of a carboxyl group-having monomer and/or 0.01 mol.% of a sulfonic group-having monomer and has a saponification degree of 60 to 95 mol.% and 0.5 to 70 pts.mass of a polyhydric alcohol selected from the group consisting of fructose, sorbitol, mannitol, sorbose, catechol, pentaerythritol and mesoerythritol. The portion-packed detergent using the film as packaging materials.