To provide an optical disk and an optical disk device, capable of smoothly reproducing desired contents in respective countries or regions even when a modulation system is different in the respective countries or regions.
The disk 10 has a plurality of recording layers (layers 0-3) in a laminating direction. The respective layers are sectioned into BCAs 12a-12d, a lead-in region 13, and a data region 14 respectively. Information modulated by ETM to correspond is recorded in the lead-in region 13 and data region 14 of the layers 0 and 1, and information modulated by FSM to correspond is recorded in the lead-in region 13 and data region 14 of the layers 2 and 3. In the BCAs of the layers 0-4, BCA information modulated by a common modulation system is held. In the BCA information, layer modulation information indicating by which modulation system the lead-in information of the respective layers and user data are modulated is held.
MATSUMURA YOSHIKUNI
TAKAHASHI SEIICHIRO
