An insulated wire, which is coated, on a conductor, with a thin-film insulating layer composed of a resin dispersion, wherein the resin dispersion contains: a polyester-series resin (A) in a continuous phase; and a resin (B) having a functional group capable of reacting with the polyester-series resin, and, if necessary, an olefin-series resin (C), in a dispersed phase; and the resin dispersion.