A method of manufacturing a magnetic recording media includes a magnetic recording layer of a granular magnetic layer that has ferromagnetic crystal grains and an oxide nonmagnetic grain boundary or a nitride nonmagnetic grain boundary surrounding the ferromagnetic crystal grains. It further has an overcoating layer on the granular magnetic recording layer. The overcoating layer contains a nonmagnetic metal or a nonmagnetic alloy that can be diffused into the nonmagnetic grain boundary. The atoms coated on the granular magnetic recording layer diffuse into the nonmagnetic grain boundary even without being annealed, and promote to isolate the ferromagnetic crystal grains from each other. The overcoating can be removed after its formation to reduce the magnetic gap between the magnetic recording layer and the magnetic recording head.