In an optical disk apparatus, a sensitivity adjusting circuit measures a
time between a reflection on a surface and a reflection on a recoding
layer of an optical disk when moving an objective lens. This time is
considered to be in accordance with sensitivity of an actuator during
layer jumping, and thereby the magnitudes of a kick pulse and a brake
pulse to be applied to the coil of the actuator is increased or decreased
in accordance with the time between the reflection on the surface and the
reflection on the recording layer. Thereby, the sensitivity dispersion of
the actuator of the optical pickup is adjusted.
