Provided are a magnetic disk substrate that can be adapted to a reduction in flying height of a head in an HDD and to an increase in rotational speed therein, and a method of manufacturing such a substrate.In an annular glass substrate for a magnetic recording medium, a main surface (12) of the glass substrate is uniformly inclined from an inner peripheral end (13) to an outer peripheral end (14) and has an isotropic shape with respect to an axis passing through the center of the glass substrate. That is, it is rotationally symmetric with respect to an arbitrary angle rotation about the axis passing through the center of the glass substrate.