A water-based dispersion composition obtained by partially or wholly neutralizing a mixture of a modified epoxy resin (A) as an emulsifying resin and an aromatic epoxy resin (B) having a number average molecular weight of 1,000 to 30,000 as a resin to be emulsified, with ammonia and/or an amine, the modified epoxy resin (A) being a modified epoxy resin obtained by reacting an aromatic epoxy resin (a1) having an epoxy equivalent of 2,000 to 20,000 with an acrylic resin (a2) having an acid value of 50 to 450 and containing acrylic acid and/or methacrylic acid, the water-based dispersion composition is applied to an internal surface of a metal can particularly required to have high processability and corrosion resistance by coating it directly on a metal material or coating it on an undercoating, baking it and drying it.