To provide a recording medium in which erasure cannot be performed and a pseudo mark in normal drive cannot be formed by forming irreversibly discrimination information being intrinsic for a disk for preventing illegal copy recorded in an optical disk or the like, and its reproducing method.
In the reproducing method of a phase transition type optical disk which is provided with land and a groove and which can rewrite information, the phase transition type optical disk is provided with a control region in which information can be recorded by a mark formed irreversibly at a region other than the recording region of user data. The mark provided irreversibly is provided continuously and integrally adjusting a phase by adjacent land and groove, reproduced data is generated by reading information of the control region in a servo-off state, and illegal copy is prevented by reproducing the user data on the basis of the reproduced data.
YAMAZAKI YUJI
IIDA TAMOTSU
SUGIYAMA TOSHINORI
SHIRAI HIROSHI
YASUI TOSHIAKI
