PURPOSE: To simply the constitution of the titled device and to reduce the device at its size by recording plural signals with prescribed frequency on a recording medium, separating these signals in a prescribed circuit and controlling a pickup on the basis of the separated frequency signals.

CONSTITUTION: Frequency signals of several tens kHz W several hundreds kHz are recorded in the inner periphery part A and an outer periphery part C of an optical disc 1 and information of several MHz is recorded in an information recording part 13. An electric signal from a photodetector 10 is inputted to a decoder circuit 17 through an RF amplifier 11, a differential circuit 12, a low pass filter 14, and comparators 15, 16. The decoder circuit 17 processes the signals from the comparators 15, 16 to detect the position of an optical head 3 and supplies its output signal to a control device 18 to control the driving of the pickup. Consequently, the pickup is prevented from projection without using a moving limit detecting means or the like, the constitution is simplified and the whole device can be reduced at its size.