PURPOSE: To make the metal mold to be needless and to prevent the generation of void when a sheet type coil conductor consisting of a foil conductor or a stripe conductor is to be wound around to form a molded coil by a method wherein the conductor being preheated and an interlayer insulating paper being heated to soften the resin are wound in layers.

CONSTITUTION: On the outer circumference of a coil former 1 providing a parting type film of ethylene tetrafluoride resin, etc., on the surface, an interlayer insulating paper 3 wider than the coil conductor 5 and being made of an insulating material consisting of glass cloth or kraft paper, etc., applying a thermosetting resin like epoxy, etc., in semisetting condition is wound around for plural turns to form a coil frame 2. Then the interlayer insulating paper 3 being heated by a heating roller 7 and a sheet type coil conductor 5 being heated similarly by a heating device 6 are wound around in layers to form an elemental coil 4. Then the coil is drawn out from the coil frame 1 and is put in lengthwise on an ethylene tetrafluoride sheet 14, spaces 13 generating in the insulating paper 3 are filled up with an epoxy resin and the outside is covered with an insulating layer 12 to form a molded coil 15.