An optical disk apparatus comprises a focusing means for focusing a light
beam on a recording medium having first and second information faces;
means for moving a focal point of the light beam in a direction
substantially perpendicular to the information faces of the recording
medium; means for detecting a reflected light from the recording medium;
means for detecting a focus condition of the light beam on the basis on
an output signal from the reflected light detecting means; a focus
control means for driving the focal point moving means on the basis of an
output signal from the focus condition detecting means, and controlling
the light beam so that the focus condition of the light beam becomes a
prescribed focus condition; and a focus jumping means for moving the
focal point of the light beam from the first information face to the
second information face by driving the focal point moving means.