An insulated wire includes a conductor, a foundation layer covering the conductor, and an insulated layer formed on the foundation layer. The foundation layer is configured with a hardening body of a resin composition including a heat curing resin having an epoxy resin, and a reactive functional group. The heat curing resin includes 1 to 10 parts by mass with respect to 100 parts by mass of the epoxy resin. Further, the heat curing resin preferably includes 5 to 30 parts by moss of blocked isocyanate with respect to 100 parts by mass of the epoxy resin.