An optical disc reading and reproducing apparatus includes reading means
for reading data recorded on an optical disc by applying laser light
through an objective lens and detecting its reflected light, focus
control means for performing focus control for moving the objective lens
based on a focus error signal indicating an amount of deviation of a
focusing position, focus bias adjustment means for adjusting a focus bias
used in the focus control to a voltage in which amplitude of an acquired
RF signal is maximized, and detection means for detecting that the
amplitude becomes smaller than a predetermined threshold level. The focus
bias adjustment means samples the RF signal and acquires the amplitude,
sets the focus bias to the amount in which the amplitude of the RF signal
is maximized, and stops sampling of the RF signal when the amplitude is
detected to be smaller than the predetermined threshold level.