PURPOSE: To facilitate automation of winding and assembling of a head, by inserting the winding with the core emptied, which is wound and shaped preliminarily, to an open magnetic shell type transformer core and by causing the core to adhere onto the plane of a plate.

CONSTITUTION: The first head core 7a and the second head core 7b are fayed to each other by glass. After the primary winding consisting of a one-turn winding 8 and a secondary winding 11 which is wound into a prescribed form preliminarily are inserted to a prescribed recess of an open magnetic transformer core 10, they are caused to adhere onto the plane of a plate of the second head core 7b, thereby constituting a one-turn head element. An open magnetic transformer core 10a is fayed to planes of the first head core 7a and the second head core 7b, and they are laminated to obtain a one-turn multielement head. Thus, automation of winding and assembling of the head is facilitated.