Patent ID: 8009547

Claim:
A recording and reproducing apparatus for an optical disk, the optical disk including: a first area on which user information is recorded; and a second area in which a plurality of marks radially extending are arranged in a track direction in the optical disk; information about a reflectance of the optical disk being recorded in the second area, as information which indicates whether the optical disk is a HL disk or a LH disk; a concentric or a spiral guide groove being formed in the first area, and address information being recorded by deflecting the guide groove in the radial direction of the optical disk; and the user information being recorded on at least one of the guide groove and an area between the guide grooves, and the following relationship holding among a track pitch TP of the first area, a wavelength λ of a light beam to be used for recording and reproducing information, and a numerical aperture NA of a light-collecting lens: 0.35×(λ/NA)≦TP≦0.7×(λ/NA), the recording and reproducing apparatus comprising: an optical head which radiates a light beam onto the optical disk; a signal processing circuit which reproduces information on the basis of a reproduced signal detected by the optical head; a gain-adjusting circuit which adjusts an amplification factor of the reproduced signal; and wherein the gain-adjusting circuit adjusts the amplification factor of the reproduced signal on the basis of the information which indicates whether the optical disk is the HL disk or the LH disk.