The present invention provides a modified epoxy resin including a structural unit derived from an epoxy compound, and a structural unit derived from an acid-terminated polyester, wherein the modified epoxy resin has a weight average molecular weight of from 1,500 to 50,000, and an epoxy equivalent of from 500 to 10,000 g/eq, and wherein the modified epoxy resin is represented by the following formula (1) (wherein, in the formula (1), n represents a number from 1 to 30, X is a structural unit derived from an epoxy compound, and Y is a structural unit derived from an acid-terminated polyester).