Optical information recording and reproducing system and optical disk.

摘要

In a read only type optical disk and a write type optical disk (1) each thereof having a data recording area (18) and a spare area (17), first encoded data for error detection and correction are recorded in the data recording area (18, 25). In the case of the read only type optical disk (1), the spare area (17) is used as a check sector (22, 31) in which second encoded data are recorded. When error correction by first error control means (7) becomes impossible while sectors in the data recording area (18, 25) are reproduced, second error control means (10) performs error correction by using the check sector (22, 31) corresponding to an associated error sector. In the case of the write type optical disk (1), the spare area (17) is used as an alternate sector. A defective sector detected by defective sector detecting means (10) is alternately recorded by being replaced by the alternate sector through sector alternating means (9).