Patent ID: 8654622

Claim:
A disc shaped information recording medium, comprising: (a) a lead-in area provided in an inner circumferential side of the disc shaped information recording medium, the lead-in area including: (1) a first read only area in which information is formed in a plurality of information tracks in spiral as a first pit area in a unit of correction block, (2) a second read only area in which information is formed in a plurality of tracks in spiral allocated in an outer circumferential side of the first read only area as a second pit area in a unit of correction block, wherein the second pit area is different from the first pit area in a physical characteristic, and (3) a third read only area in which information is formed in a plurality of tracks in spiral as a third pit area in a unit of correction block, allocated between the first pit area and the second pit area, wherein in order to track continuously the disc shaped information recording medium in an apparatus for reproducing the disc shaped information recording medium, the third pit area is formed such that a physical characteristic of at least three tracks in a plurality of tracks in the third pit area changes gradually from a physical characteristic in the first pit area to a physical characteristic in the second pit area so as to adjust a physical characteristic difference between the first pit area and the second pit area; and (b) an information track area provided in an outer circumferential side of the lead-in area in which information is recorded in a unit of correction block.