PURPOSE:To always shift to a focusing pull-in state at an optimum time by bringing an input focusing shift signal to A/D conversion in a state before focusing pull-in in a focusing control circuit, deriving an average value in a prescribed period, and generating a focusing signal when the shift is equal to the average value. CONSTITUTION:A focusing shift signal SFE which has passed through an amplifying circuit 3 is brought to A/D conversion by a signal CKGEN of a circuit 23 based on a clock CLK from a control circuit 22 and goes to a signal DTFE. Based on the signal CKGEN, a phase compensating circuit 24 inputs a focusing servo-signal DTSB to a terminal (a) of a switching circuit 7. An FZC detecting circuit 25 generates a detecting signal DTFZC, based on a control signal CNTFZC. A servo-control circuit 26 generates a signal CNTPSI, based on a control signal CNTSB and the DTFZC, controls a focusing scanning circuit 27, and selects an input end of the switching circuit 7 by DTFS and CNTSWI. Subsequently, the output of the switching circuit 7 goes to a focusing coil driving signal SDV through a decoder 28, and an objective lens is driven in accordance with the DTSB or the DTFS through a driving circuit 9. According to such a constitution, it is always possible to enter into a focusing state at an optimum time irrespective of a value of a focusing bias signal.
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