A plate-like coil formed by a metal plate is buried in a base made from an insulating material in a state in which electrode terminals and a fixing terminal of the plate-like coil are projecting from the base. The base has through-holes in which a central leg and side legs of an E-shaped core are to be inserted. The E-shaped core and an I-shaped core are mounted to the base while holding the base therebetween, and the electrode terminals and the fixing terminal projecting from the base are bent to the bottom surface of the base. Each of an electrode terminal bent portion located bottom surface portion at which the electrode terminals are to be disposed and a fixing terminal bent portion located bottom surface portion at which the fixing terminal is to be disposed is positioned upwardly from a base bottom portion, and a recessed groove is provided between the base bottom portion and each of the electrode terminal bent portion located bottom surface portion and the fixing terminal bent portion located bottom surface portion.