PURPOSE:To improve the wear resistance of a magnetic head and to attain long life, by forming a notch at least at corners of a contact part of the recording medium of a magnetic core and forming a glass layer including SiC on the notch. CONSTITUTION:Notches 11 are formed at corners of a sliding contact surface 5 and a gap forming surface 9 of a C shaped core blank material 1a and an I shaped core blank material 2a and at corners of the sliding contact surface 5 and an outer side surface 10. Wear-resistant glass including = 50wt% SiC (to the total weight of the glass) of <=10mu average particle diameter or <=50mu average fiber diameter, to a glass layer comparatively high content of a low melting point oxide such as PbO and B2O3, is poured in the core blank materials 1a and 2a located in a mold. After forming a glass layer 12 by cooling, the materials are cut off at a position shown in one-dot chain lines to obtain individual magnetic cores 3. Thus, the magnetic head less in the dispersion of durable life and with long life can be obtained.