Patent ID: 7196975

Claim:
An optical disk device comprising a floating-type or a sliding-type magnetic head and an optical head, the optical disk device performing recording and/or reproduction with respect to a magnetic field modulation type magneto-optical disk, a read-only disk, and an optical disk comprising an optical disk substrate of a predetermined thickness having a light incidence surface on one face, in which at least a pit information surface and a protective layer are formed in this order on a side of the other face opposed to the light incidence surface, wherein the protective layer is a protective layer that is used in a magnetic field modulation type magneto-optical disk and formed of an ultraviolet curable resin layer coated with a silicone oil, wherein the magnetic head is retracted when mounting the magneto-optical disk, the read-only disk, and the optical disk, the magnetic head is separated from the read-only optical disk when performing reproduction with respect to the read-only optical disk, and the magnetic head is allowed to slide or float when performing recording and reproduction with respect to the magneto-optical disk and the optical disk.