PURPOSE: To prevent the deflected wear of a head core and its case and at the same time increase a magnetic shielding factor, by forming the case after burying a material having wear resistance equal to a head core material into a plate material of the case with the prescribed width and depth and then applying a grinding process to a sliding surface.

CONSTITUTION: A material (stainless steel, etc.) 4 having wear resistance equal to a magnetic head core material is previously buried in a belt form having a prescribed width Z to a plate material of "Permalloy ". Then a recessing process is applied to the part of the material 4 so as to obtain the length Y, width Z and depth X respectively at the upper part of an opening part 3a to which a head core is set opposite, and a drawing process is applied to a case 3. The head core is stored into the case 3, and the sliding surface of a recording medium is removed by grinding up to the position shown by a chain line 5. Thus a grinding back surface M is formed from a grinding front surface N. Thus the part of the stainless steel 4a (shown by a dotted line) which received no recessing process is deleted. In such a way, the sliding surface between the head core and the case 3 is formed in a continuous state to prevent deflected wear. Furthermore, the magnetic shielding factor is increased.