PURPOSE: To improve durability and weather resistance of an iron-group magnetic thin film essentially comprising iron, carbon, and nitrogen by providing an oxide film on the surface of the magnetic thin film.

CONSTITUTION: An oxide film 8 is provided on the surface of the magnetic thin film 3 essentially comprising iron, carbon, and nitrogen. Carbon and nitrogen have such as effect to give stability and durability of the iron compd., and the iron compd. thin film is covered with an oxide thin film having high stability which functions as a protective film or a self-lubricating film. The oxide film is formed by sputtering or vapor deposition to the carbonized iron compd. thin film, or the carbonized-ion compd. thin film is subjected to heat treatment in an atmosphere containing oxygen to form a heat-oxidation film. Thereby, durability and weather resistance of the iron-group thin film can be improved.