An optical disk apparatus of the present invention measures a surface deflection component (shape of surface deflection) from a low-pass component of a compensating filter in a surface deflection measuring part provided in a DSP. Furthermore, the optical disk apparatus calculates timing at which a positional change in a surface deflection component in time required for focus jumping is a predetermined value or less in a timing calculating part, and starts focus jumping at the timing. Because of this, stable focus jumping is made possible.