PURPOSE: To contrive an efficient winding work by providing an inner layer insulation inside the insulation of a strand or in the insulation of the strand along the direction of the length.

CONSTITUTION: An inner layer insulation 5 has a shape of fitting on a conductor 1 and when it is fitted on the conductor 1, it is wrapped with a strand insulation 2. If the conductor for coil is wound into a coil as shown in the drawing, the inner layer insulation 5 is located between the conductors and accordingly, insulation becomes effective. If the inner layer insulation 5 is arranged on both sides of the conductor 1 and is used as a coil. The interlayer insulation can be as much effective as 52 inner layer insulations. If the inner layer insulation 5 is provided on top and bottom of the conductor 1 and it is wound into a coil, the insulation is intensified between the adjacent conductors 1 rather than that of the interlayers. Moreover, if the inner layer insulation 5 is provided within a strand insulation 2, a coil wound with this wire also can obtain an effect of insulation between the layers.