An optical disc having a plurality of sectors, each of which includes a plurality of frames. Sub information bit value '0' or '1' is assigned to the plurality of frames constituting a sector, excluding the first and last frames. Edge positions are displaced so that leading/lagging errors appear in accordance with a certain rule when data fields of the frames to which sub information bit value '1' is assigned are read. Edge positions are displaced so that leading/lagging errors appear in accordance with a reversed rule of the certain rule when data fields of the frames to which sub information bit value '0' is assigned are read.