PURPOSE: To use an optical disk whose track areas can be identified by reproducing information signals for identifying areas with an optical head and in which track areas of reproduction only, postscript only, etc., are mixedly provided, by previously providing the area identifying information signals on part of the track as pits.

CONSTITUTION: Annular areas represented by RA, RB, and RC are used as a track area for postscript, area for reproduction only, and area for erasion, respectively. An index field 3 is composed of an index mark 4 and jumping area 5. Each sector 6 has a sector header area 7 followed by a data field (D0WDn)8 in which recorded data are accumulated at the first section. The index mark 4 of the index field 3 retraces the same track at every turn. It can be discriminated by detecting the reproducing signal of an area identifying signal section 9 that which kind of track area of this optical disk is reproduced and, when the postscript type track area is reproduced, suitable measures and control, such as inhibition of irradiation of an earsing light beam, for performing the recording and reproduction of the postscript type optical disk are performed. Therefore, this optical disk can be operated with one set of optical disk device.