An optical disk on which data is recorded optically, having a plurality of sectors, each sector having a data region to be recorded with data, the data being recorded in units of blocks, the block being a data unit which includes a predetermined number of sectors and to which error correction is applied, wherein
- in recording data related to a content by dividing and recording the data in a plurality of continuous sectors,
- dummy data is recorded on a region adjacent before a sector from which data recording is started, the dummy data is used for extracting a clock for data reproduction, and
- the data related to the contents is recorded on sectors following the region recorded with the dummy data.