PURPOSE: To make an adhesive layer uniform to make the characteristic uniform and reduce the cost by providing the second core part with a groove corresponding to the outside shape of the first core part and providing the first core part in this groove as one body.

CONSTITUTION: Metallic magnetic bodies 32 and 33 form metallic cores 15 and 16 in grooves 30 and 31 for track and form grooves 12c and 13c for winding in rear parts 26d and 27d of ferrite blocks 26 and 27. After faces 26e and 27e facing each other are formed to flat surfaces, a window groove 12d for winding is formed on the face 26e of one ferrite block 26. After an SiO2 thin film is provided on said faces 26e and 27e, metallic cores 32 and 33 are so butted that joint parts 32a and 33a of them form a prescribed track width W, and they are fixed by a jig or the like, and ferrite blocks 26 and 27 are joined into one body by an adhesive. Thus, the yield is good and mass production is possible to have the advantage of cost because the structure is stout.