in the subtractor 25 the difference between the amplitude values of the reproduced signals from the tracking error detecting pits 1 and 2 is calculated whereby a tracking error signal is produced on the other hand by means of the adder 28 and divider 29 the value of the sum of the amplitude values 41 and 42 multiplied by 1 4 namely the average values is calculated the divider 29 is realized in practice by adapting such that the output of the adder 28 is shifted therein by one bit the comparator 30 compares the aforesaid average value with the amplitude value of the pit 3 is magnitude and outputs the result to the register 26 the register 26 while storing therein the tracking error signal according to the output of the subtractor 25 resets the value to 34 0 34 when the amplitude value 43 of the pit 3 is smaller than the aforesaid average value namely when the light beam is positioned in the middle of adjoining tracks the d a converter 27 converts the thus calculated tracking error signal back to an analog value the operation of the embodiment of fig4 will be described again will reference to fig6 a to 6d when the light beam moves in the direction of the track the envelopes of the signal amplitude values of the three pits vary as indicated by 5 6 7 fig6 a therefore.