In a magnetic disk having a magnetic layer, a protection layer, and a
lubrication layer formed on a substrate in this order, a surface free
energy .gamma.S of a surface of the magnetic disk derived by an extended
Fowkes equation is greater than 0 and no greater than 24 mN/m. .gamma.Sd
(dispersion force component of surface free energy) forming the surface
free energy .gamma.S is greater than 0 and no greater than 17 mN/m,
.gamma.Sp (dipole component of surface free energy) forming the surface
free energy .gamma.S is greater than 0 and no greater than 1 mN/m, and
.gamma.Sh (hydrogen bonding force component of surface free energy)
forming the surface free energy .gamma.S is greater than 0 and no greater
than 6 mN/m.