Patent ID: 7333405

Claim:
A control circuit of an optical disk device for performing information recording or reproduction with respect to a multi-layer optical disk that has a plurality of recording layers including a first recording layer and a second recording layer that are adjacent to each other, the optical disk device comprising: an optical pickup including a laser light source, a convergent optical system having an objective lens that receives a light beam emitted from the laser light source, and converges a microspot on an optical disk, and an aberration correcting optical system that controls a spherical aberration of the convergent optical system, wherein an operation of changing a correction quantity of the spherical aberration is started so that the correction quantity of the spherical aberration approaches from a value adequate for recording or reproduction with respect to the first recording layer to a value adequate for recording or reproduction with respect to the second recording layer before an operation of moving a focus position of the microspot from the first layer to the second layer is completed.