To strengthen adhering of a core material and an umbrella material without employing a special primer, improve insulation property, and reduce manufacturing cost by winding a roving formed by an insulation material around an outer periphery of an insulation core material, making the insulation umbrella material of a silicon resin and making an insulation core material of a composite material consisting of an epoxy resin and a glass fiber.

An insulation umbrella member 2 is provided around an outer periphery of a insulation core member 1 made of a synthetic resin formed by a pulling out and molding method, and a wire mount part 3 mounting and holding a wire is provided upside or downside of the insulation core member 1. A roving 4 formed of an insulation material is wound around an outer periphery of the insulation core member 1, the insulation umbrella member 2 is made of a silicon resin, the insulation core member 1 is made of a composite material made of an epoxy resin and a glass fiber, and a roving 4 is a glass roving. Since a ragged part can be formed on the outer periphery face of the insulation core member 1 by winding the roving 4, this ragged part has a projection effect, and the insulation core member 1 and the insulation umbrella member 2 can be adhered rigidly.