PURPOSE: To contrive accomplishment of low cost and miniaturization of the titled transfomer by a method wherein the insulating plate having the metal printed wiring on which a part of wiring and a circuit are formed, an insulating material with a through hole, and a toroidal core are formed in an integral structure.

CONSTITUTION: A core 13 and an insulating material 14 are pinched between insulating plates 11 and 12, a metal printed wiring 5a is connected to a metal printed wiring 7a through the intermediary of a through hole 3a, and the wiring 7a is connected to a metal wiring 5b through the intermediary of a through hole 3b. Therefore, a single wiring is formed around a toroidal core 13 by the line constituted by wirings 5a, 7a and 5b. A multiple-wound wiring is formed by repeating the connection same as above a plurality of times. Through these procedures, a necessary primary winding can be obtained. The necessary secondary winding can be obtained by successively connecting metal printed wirings 6aW6c, 8a, 8b and through holes 4aW4c and the like. Also, when a circuit having a metal printed wiring is provided on insulating plates 11 and 12, and the transformer and said circuits are connected, connecting works are unnecessitated.