To eliminate the trouble to laminate green sheets on which two coil elements that are of nearly 3/4 turn and arranged in a concentric manner have been formed respectively, rotating each green sheet by an angle of 90°, and to solve a problem in which an inner coil has small inductance, and an outer foil has large inductance, so that a primary coil and a secondary coil are not equal to each other in inductance, and a transformer having a voltage step-up ratio 1:1 is hardly formed.

Insulating layers on which two coils have been formed respectively are laminated, and the coils formed on the insulating layers are connected in interlayer for the formation of a transformer. At the intermediate part of the transformer, a coil of one turn is divided into two unequal parts, the layers which are of two kinds and equipped with interlayer connecting parts are alternately laminated on the ends of the unequally divided coils respectively, the two divided coils are formed into a concentric coil of one turn respectively, the concentric coils are laminated and fixed together into a laminate of integral structure by application of pressure, and the laminate is baked into a laminated transformer.