PURPOSE:To facilitate the formation of fine wires as well as to prevent breaking and tangling of wires by a method wherein a conductive coil pattern is formed on a flexible insulating film, and after it has been cut as prescribed, a cored winding is formed by winding the above on a core. CONSTITUTION:A coil pattern of almost rectangular shape is formed in deposition on one side of a long-sized flexible insulating film 1 using a conductive film 2. The film 1 is cut along the line linking between points A and B and formed into two branched parts. The non-cut part 1b is placed on an I-shaped core 3 in such a manner that it is intersecting at right angle with the core 3, one of the branched parts of (m) and (n) of the film is wound around a core 3 counterclockwisely, and the other part is wound around clockwisely. Then, both parts of (m) and (n) are arranged in the condition they were before cutting by arranging the end parts of them side by side on the same plane surface on one side of the core so that the cut side of the conductive film 2 at the point A side and part 1a are facing each other. Subsequently, the opposed cut faces of the conductive film 2 are electrically bonded by solder 4, and the conductive film 2 is connected as in the original state.