To provide a method for manufacturing a glass substrate for a magnetic disk, which method can manufacture the glass substrate for the magnetic disk having a stable quality, at a low cost in large quantities, by simply and excellently polishing the inside end surface portion of a circular hole, particularly its chamfered surface, provided at a central portion of the glass substrate for the magnetic disk even if the hole is small sized, and further which method can prevent the thermal asperity obstruction and the head crush in the magnetic disk, and can achieve the high density of the information recording surface of the magnetic disk.

A polishing fluid containing loose abrasive grains, which have a plurality of polishing abrasive grains on a base grain, is supplied on the end face of the inner peripheral side of the glass substrate 2 for the magnetic disk. The end face of the inner peripheral side of the glass substrate is polished so as to have a mirror surface by relatively moving the end face of the inner peripheral side of the glass substrate, a polishing brush 3, and a polishing pad or a polishing table, respectively.