Provided is a process for manufacturing a magnetic recording medium having a magnetically partitioned magnetic recording patterns, which comprises the following steps, conducted in the order: (1) step of forming a magnetic layer on a non-magnetic substrate, (2) step of exposing the surface of regions of the magnetic layer to a reactive plasma or a reactive ion, which regions are to magnetically partition the magnetic layer for forming a magnetically partitioned magnetic recording pattern, and (3) step of exposing the magnetically partitioned magnetic layer to an inert gas irradiation. Preferably, a step of removing surface layer portions of said regions of the magnetic layer is carried out after the step (1) but before the step (2). The surface of the magnetic layer of produced magnetic recording medium exhibits good resistance to corrosion caused by oxidation or halogenation.