An improvement is proposed in the method for the preparation of a magnetic recording medium by forming a magnetic recording layer of a magnetic alloy on the surface of a non-magnetic substrate plate of, e.g., silicon so as to impart the magnetic recording medium with improved CSS (contact-start-stop) characteristics still without affecting the magnetic recording density. The improvement can be obtained by subjecting the surface of the substrate plate, prior to the formation of the magnetic recording layer, to a surface-roughening treatment which is performed either by a dry-process such as plasma etching and reactive ion etching or by a wet-process of anisotropic etching by using an aqueous solution of sodium or potassium hydroxide as the anisotropic etching solution. In particular, the plasma etching or reactive ion etching is conducted in the presence of a particulate scattering source body of aluminum, etc. placed in the vicinity of the CSS zone so that the surface-roughening effect is limited to the CSS zone by the deposition of particulates scattered therefrom leaving the recording zone unroughened not to decrease the recording density.