Optical disk apparatus

An optical disk apparatus, comprising:

• a moving part for moving a converged point of a light beam converged on a recording medium having a plurality of stacked recording/reproducing surfaces in a direction substantially vertical to the recording/reproducing surfaces;
• a converged state detecting part for generating a signal corresponding to a converged state of the light beam on the recording medium;
• a focus control part for driving the moving part in accordance with a focus error signal that is an output signal from the converged state detecting part, in such a manner that the light beam is converged at a substantially constant position on the recording medium;
• a focus jumping part for moving the converged point of the light beam from an arbitrary recording/reproducing surface of the recording medium to another recording/reproducing surface thereof;
• a surface deflection measuring part for measuring a shape of surface deflection of the recording medium;
• a surface deflection storing part for storing the measurement results of the surface deflection measuring part in a memory successively on a predetermined phase basis over one rotation of the recording medium;
• a converged position holding part for holding a converged position of the light beam at the beginning of focus jumping;
• and
• a surface deflection correcting part for updating the converged position of the light beam held by the converged position holding part during focus jumping, based on the stored values in the surface deflection storing part.