Abstract: A coil bobbin of molded resin integrally for use of a magnetic head core comprising a pair of connection plates arranged in parallel, a pair of coil winding bodies formed in U-letter shape with a rear plate, an inner side plate and an outer side plate, which are to be mounted on a pair of parallel leg portions of a magnetic head core respectively and arranged between the connection plates with the opening side in one direction, inclination surfaces provided on the tip of each side plate and obliqued toward the opening of the coil winding body respectively and hooks formed by being elongated continuously from said inclination surfaces and projected in the opening, which are provided merely on the outer side plates and hooked on each rear side of the legs of the magnetic head core.