With the use of a novel method in which after a magnetic recording medium carrying a ferromagnetic metal thin film is heated, a protective layer is developed on the ferromagnetic metal thin film by a known plasma CVD technique while an out gas from the magnetic recording medium being eliminated by absorption, another method in which a ferromagnetic metal thin film and a protective layer are formed in succession within a vacuum chamber, or a further method in which after a non-magnetic substrate is heated, a ferromagnetic metal thin film and a protective layer are formed in succession within a vacuum chamber while an out gas from the non-magnetic substrate and the ferromagnetic metal thin film being eliminated by absorption, the atomic ratio of the hydroxyl group to a primary component metal element contained in the ferromagnetic metal thin film can be decreased at the interface between the ferromagnetic metal thin film and the protective layer.