PURPOSE: To enhance intimate adhesion between a thin ferromagnetic metallic film and a protective layer and resistances to abrasion and corrosion by forming a metallic layer capable of reacting with a higher fatty acid to form its metal salt before forming the protective layer.

CONSTITUTION: A thin ferromagnetic film 2 is formed on a base 1 of a film made of a polymer, such as polyester by depositing a metal, such as Ni, through the sputtering process or the like. A metal layer 3 is formed by depositing a metal capable of reacting with a higher fatty acid and forming its metal salt on the surface of said film 2 by the vacuum evaporation method. As said metal, elements of group IV, such as Ti, those of group VI, such as Cr, and those of group VII, such as Mn, are used. After the layer 3 is formed, a protective layer 4 is formed on the layer 3 by coating it with the molted liquid or a soln. obtained by dissolving this in a solvent. As the higher fatty acid, palmitic acid, etc. are used. Since the protective layer 4 made of the fatty acid is not formed directly on the surface of the layer 2, the metal layer 3 is inserted, the layer 2 is affinitive to the layer 3, and adhesion and intimate contact are enhanced between them.