Optical disk and an optical disk recording reproduction device

An optical disk recording/reproduction device for an optical disk of a land and groove recording/reproduction type including a plurality of sectors each having a sector address region and a data region,

• wherein the sector address region of the optical disk includes a plurality of address blocks, at least two of the plurality of address blocks that adjoin each other along a circumference direction being disposed on a boundary line between the land and the groove so as to be shifted toward opposite sides with respect to a track center, and
• each of the plurality of address blocks includes a portion indicating an address number for identifying the plurality of sectors from one another and a portion indicating an ID number for identifying the plurality of address blocks from one another within the sector address region, and
• wherein the recording/reproduction device comprises:
• an optical head for radiating a light beam on the optical disk and receiving light reflected from the optical disk so as to output a reproduced signal;
• and
• an address signal reproduction section for reading the address number and the ID number when reproducing the sector address of the optical disk.