An insulated electric wire includes a conductor and an insulating layer. This insulating layer is made of a resin composition containing a base polymer and a metallic hydroxide. The base polymer contains ethylene-vinyl acetate copolymer and ethylene-(α-olefin) copolymer. The “α-olefin” is a non-polarized monomer, its melting point is equal to or lower than 70° C. A vinyl-acetate total content of the base polymer is equal to or less than 19 mass %. The resin composition contains the ethylene-(α-olefin) copolymer, a content of which is equal to or more than 20 parts by mass and equal to or less than 70 parts by mass per 100 parts by mass of the base polymer, and contains the metallic hydroxide, a content of which is equal to or more than 30 parts by mass and equal to or less than 150 parts by mass per 100 parts by mass of the base polymer.