PURPOSE: To obtain structure having an excellent stationary stability of a wire rod and also having superior cooling properties of the inside by rolling in spacers among the layers of a winding at the same time as a coil is wound and forming a cooling channel, into which a refrigerant flows, in a coil impregnated with a resin and cured, using the spacers as molding dies.

CONSTITUTION: Spacers are inserted among each layer of a winding or among layers at every one or several layer during winding work. When the whole coil is wound completely, the winding is impregnated with an epoxy resin 2, formal, etc., through vacuum-drawing, the resin, formal, etc., are cured and the fine spaces of a winding section and the clearances of insulator layers shaped to the surface of a wire rod are buried, and the whole coil is fixed by the impregnant so that the wire rod is not moved. When the impregnant is cured sufficiently, cooling channels 3 shaped by the spacers are formed among layers of the winding by the removal, etc., of the spacers. Accordingly, the two of the stationary stabilization of the winding and efficient cooling are enabled.