PURPOSE: To increase the conductor occupying rate of a coil and to reduce the size and the thickness of the coil by winding the band of square in cross section so that the insulating layer makes contact with the conductive foil in predetermined configuration.

CONSTITUTION: An insulator 12 is coated on a cleaned conductor foil 11, an adhesive such as epoxy resin is coated thereon, and wound so that the insulating layer 12 makes contact with the conductive foil 11. Then, the cylindrical body is filled in a mold, to be formed in desired shape, the epoxy resin is hardened, and cut in predetermined thickness to form a coil of thin plate. An epoxy resin 17 is coated in large thickness so at not to entangle the conductor foil 18 wound thereon at cutting time. The coil may not be cut perpendicularly but the burr at cutting time is removed by aqueous ferric chloride solution as etched. The conductive foil wound is disposed at a plurality of positions and cut simultaneously therat. Thus, the conductor occupying rate of the coil may be increased and the size and thickness of the coil may be reduced.