OPTICAL DISK DEVICE, INFORMATION RECORDING AND REPRODUCING METHOD THEREOF, AND CONTROL CIRCUIT

PROBLEM TO BE SOLVED: To perform recording and reproducing to/from a multilayer optical disk having at least first and second recording layers, by use of an objective lens having NA of at least 0.8, while ensuring stable interlayer jump.SOLUTION: An optical disk device is provided with an optical pickup that includes a convergent optical system having an objective lens for converging a light beam emitted from a laser light source to form a microspot on an optical disk, and an aberration correcting optical system for controlling a spherical aberration of the convergent optical system. In the optical disk device, an operation of changing a correction quantity of the spherical aberration from a value adequate for the first recording layer to a predetermined value is started before an operation of moving a focus position of the microspot from the first layer to the second layer is completed. This allows stable focus control with respect to the second recording layer with a spherical aberration corrected, thereby preventing the focus control from failing due to an unsuccessful interlayer jump.