PURPOSE: To facilitate an automatic winding as well as to reduce a number of manufacturing processes largely by forming a duct into a L-shape which is provided between layers being wound, and by holding an end of an insulation tape with the bent section of the L-shaped duct, thereby preventing a paper in between the layers from falling onto the duct surface.

CONSTITUTION: A beginning section 2a of a coil is fixed on a predetermined position of a coil bobbin 1, and then, a beginning section 31a-1 of an insulation tape is fixed. Next, a coil wire 2a is wound in an arrowed direction. At the same time, the insulation tape is laminated to form an end-section insulator 31a. Then, the coil wire 2a is wound up to a number 2b required for the first layer, and its end is held by a duct 41 that has a L-shaped hook 41a. With this condition, the coil wire 2 is shifted from the ending section 2b of the first layer to a beginning section of the second layer, and is wound on the duct 41. The insulation tape is also shifted to the second layer to form an insulator 31b for the second layer, thus facilitating an automatic winding.