PURPOSE: To obtain an insulation wire ring of good quality by manufacturing it in such a manner that a pre-pregnant mica tape is wound in an inner layer near a conductor, a pre-pregnant glass tape is wound around thereon, a plate is placed thereon, a thermal contraction tape is wound and then it is heated for solidification.

CONSTITUTION: A resin, molten at a temperature between 50 and 60°C, is applied onto a glass-lining mica sheet or a base cloth of a glass, etc., and after having been dried by being heated at a temperature between 70 and 80°C, it is again dried reduced pressure at 1 torr and a temperature between 70W80°C to prepare a non- solvent pre-pregnant tape. And then, a conductor 7 having cooling media penetrating pores 6 is fixed with an insulation material 8, such as an epoxy pre-pregnant alamide paper, etc., to prepare a wire ring (or a wire coil). A mica tape 9 and a glass tape 10 are wound in an inner layer near the conductor 7, the exterior surface is covered with a steel plate 11, a high tension thermal contraction tape 13 is wound through a rubber elastic body 11 and then it is heated for solidification. A thick insulation wire coil with mechanically and electrically high strength is obtained by removing the steel plate 11, the rubber elastic body 12 and the tape 13 after completion of the solidification.