Magnetic recording medium having a cobalt-based alloy film for high density recording and magnetic storage device using same

In one embodiment, a magnetic recording medium comprises an underlying film, a magnetic film and a protective film formed in this order on a substrate. The magnetic film is a cobalt-base alloy film containing chromium and has a plurality of magnetic layers stacked without interposition of any non-magnetic layer. The plural magnetic layers comprise first, second and third magnetic layers. The first magnetic layer is disposed between the underlying film and the second magnetic layer. The second magnetic layer is disposed between the first magnetic layer and the third magnetic layer. The third magnetic layer is disposed between the second magnetic layer and the protective film. The concentration of chromium contained in the first magnetic layer is lower than that of chromium contained in the second magnetic layer. The thickness of the first magnetic layer is smaller than that of the second magnetic layer. The magnetic layers which overlie the first magnetic layer further contain platinum and boron. The concentration of chromium contained in the third magnetic layer is lower than that of chromium contained in the second magnetic layer.