Processing and manufacturing method of a master for optical disk, the master for optical disk, a manufacturing method of an optical disk substrate, the optical disk substrate, and a processing device of a master for optical disk

A processing method of a master for optical disk for forming grooves which configure a groove track, prepit groups on the same spiral or circumference as said groove track and prepit groups on the same spiral or circumference as a land track neighboring said groove track, comprising:

• a process for irradiating a laser beam on the master on which photosensitive material is coated in order to form prepit groups on the same spiral or circumference as said groove track;
• and
• a process for irradiating a laser beam on said master in order to form prepit groups on the same spiral or circumference as said land track,
• wherein each said irradiating process is alternately conducted by sequentially switching radial positions of irradiating a laser beam for forming the prepit groups while changing a circumferential position of said laser beam for forming the prepit groups on said master.