An information recording and reproducing apparatus records and reproduces information in and from a recording medium (11) including an information recording region divided into a plurality of sectors. In recording and reproducing information in and from the recording medium, each sector includes a sector address part (1) formatted and a data recording part (5) for recording data. A predetermined signal is overwritten in the address of a sector thereby to make reproduction of the address impossible to prevent data from being recorded again by error in the sector containing data, while at the same time protecting the writing in the sectors. in data recording, on the other hand, the address signal from the recording medium (11) is binary-coded at a different level to detect a sector of unstable address reproduction, so that a predetermined signal is overwritten in the address of this sector to make subsequent reproduction of the address impossible, thus permitting recording only in the sectors of stable address reproduction for stable data reproduction. Further, an optical disc (11) having sectors of stable address reproduction alone detects a sector of unstable reproduction at the time of inspection, and overwrites a predetermined signal in the address part (1) of the particular sector to make subsequent reproduction of the address impossible.