A glass for a magnetic recording medium substrate permitting the realization of a magnetic recording medium substrate affording good chemical durability and having an extremely flat surface, a magnetic recording medium substrate comprised of this glass, a magnetic recording medium equipped with this substrate, and methods of manufacturing the same. The glass compositions disclosed comprise oxides of at least Si, Al, Li, Na, K, Sn and Ce, optionally Sb, but not comprising As or F. Additional oxides of Mg, Cs, Sr and Ba may be present. The oxides are presented as molar percentages, mass percentages and ratios thereof.