MANUFACTURING METHOD OF GLASS SUBSTRATE FOR MAGNETIC DISK AND MANUFACTURING METHOD OF MAGNETIC DISK

PROBLEM TO BE SOLVED: To provide a manufacturing method of a glass substrate for a magnetic disk, capable of improving processing quality with enhanced yield in manufacturing a glass substrate for a magnetic disk by cutting out of a plate glass material.SOLUTION: A manufacturing method of a glass substrate for a magnetic disk uses a glass sheet material having dimensions allowing a plurality of glass substrates for magnetic disks to be cut out thereof. Scribed curved lines along approximate peripheries of regions to be processed into glass substrates for magnetic disks are formed on one principal surface of the glass sheet material. Subsequently, the temperature of the glass sheet material is changed to advance the scribed lines, so that the plurality of disk-shaped glass substrates are cut out of the one glass sheet material.