PURPOSE: To obtain a resin composition for insulated wire excellent in flexibility, adhesion, heat resistance, deterioration resistance, and solvent resistance, by mixing a specified polyester resin, a resol type phenol resin, and a polyhydantoin resin.

CONSTITUTION: Resin composition for insulated wire is composed of (A) polyester resin which has an imide bond in a moleculer chain obtained by using tris-2- hydroxyethylisocyanurate for a part of alcohol compound, (B) resol type phenol resin, and (C) polyhydantoin resin obtained by reacting (i) glycine derivative expressed in a general expression as indicated in the figure, with (ii) 4,4' di- isocyanate diphenylmethane. 0.5-7weight% of (B) resol type phenol resin, or 3-20weight% of (C) polyhydantoin resin are mixed with (A) polyester resin.