PURPOSE: To make possible a simple insulating coating treatment of a wound conductor and to make it possible to mold integrally a wound coil without applying a strained force to the wound coil in its mechanical fixing by a method wherein the wound coil is constituted using a conductor obtainable by performing an electrostatic coating of a powder body epoxy resin on the surface of an aluminum conductor as a wire material.

CONSTITUTION: A powder body epoxy resin 4 is applied on the surface of an aluminum conductor 1 by electrostatic coating as an insulating treatment of a wire material. The thickness of a coat film, which is formed on the surface of the conductor 1, can be chosen from among film thicknesses to respond to the purpose of use of the coat film. The aluminum wire material subjected to surface treatment in such a way is wound, is molded with a molding resin 3 and a ground coil is constituted. Thereby, the coil can be constituted significantly thinner than the coating thickness of a conventional wire material. Consequently, it can be formed into a wound coil having a large space factor and having a small section. Moreover, the work of assembly of a winding prior to the molding is simplified and the manufacturing cost of a ground coil for railroad use can be reduced.