An optical disk apparatus includes a photodetector divided into eight segments which receive the laser beam reflected from the optical disk and produce signals based on the laser beam sport thereon. In this apparatus, these eight segments are combined in several patterns for the recorded information reproduction, the tracking error detection, and the focus error detection, respectively. For the recorded information reproduction, eight segments are used as combined in three segment cells RC1, RC2, and RC3 which extend in a direction parallel to each other such that the segment cell RC1 is in center and is sandwitched by other segment cell RC2 and RC3. The segment cells RC1, RC2, and RC3 are located perpendicular to the recording track of the optical disk and produce three signals C, R, and L indicative of the laser beam intensity of the laser beam spot thereon, respectively. Thus obtained signals C is multiplied by a constant K and then added to the other signals R and L. By selecting suitable value as the constant K, the crosstalk component in the reproduced signal can be reduced.