PURPOSE: To manufacture a resin-impregnated and molded coil whose cost is low and which is excellent in electric properties etc. and appropriate to a transformer or the like, by winding a conductor to make a plurality of conductor 1 layers, laying a wave-shaped insulator to divide the conductor layers in the radial direction and make a resin duct and impregnating a resin.

CONSTITUTION: A conductor is wound around a bobbin frame 1 to make a plurality of conductor layers for a coil. A polyester mat 8a is inserted for a resin duct along the entire or partial circumference of the coil 2. A wave-shaped duct 8b is inserted into the polyester mat 8a to prevent the mat from being compressed to a high density by the upper coil. The resin duct 8 is thus made to provide a resin passage to impregnate the coil 2 with resin. This results in improving the impregnating property of the coil and making its mechanical, electrical and thermal characteristics excellent.