PURPOSE: To improve durability by providing an amorphous protective film layer on a magnetic layer by the combination of respective atoms; carbon atom, oxygen atom, hydrogen atom, and fluorine atom, and depositing the protective film layer securely onto the magnetic layer.

CONSTITUTION: The amorphous protective film layer 11 which consists of the respective atoms; carbon atom, oxygen atom and hydrogen atom or said atoms and the fluorine atoms or the respective atoms; carbon atom, oxygen atom and fluorine atom, and contains the oxygen atom at the ratio higher in the boundary layer with the magnetic layer 10 than in the surface layer is formed. The protective film layer 11 formed in such a manner is satisfactorily improved in the adhesiveness to the magnetic layer by the oxygen atom contained much in the boundary layer and the protective film layer 11 is securely deposited on the magnetic layer 10, by which the durability is additionally improved without generating the worn powder by the defective adhesion and the exfoliation, etc., of the protective film layer 11.