Abstract: A process for producing a flat coil of high reliability and free from the problem of short-circuiting, and capable of high productivity. The process includes steps of forming an insulator layer on a metal foil ribbon, winding the metal foil around a center shaft or mandrel while pressing the insulator layer toward the center shaft to form a rolled up metal foil body. A strip electrode of conductive metal may be integrally attached to the inner or outer periphery of the coil or both to provide electrical connection to the turns. An insulating resin layer may be formed at an outer end of the metal foil, and a metal reinforcing layer can be formed on the outer periphery of the rolled up body other than at the insulating resin layer by electroplating to form a coil block. The rolled up body or coil block is then cut by electric discharge machining in a direction transverse to the center shaft to form flat coils at a predetermined thickness.