CD-ROM device

Provided is an optical disk device that allows the implementation of steady focus control or tracking control. A first detector (110) receives light reflected from an objective lens optical system (107). A second detector (112) receives light reflected from a predetermined information layer. On the basis of signals from the second detector (112), a position aberration detection unit (121) detects positional aberrations between the focal point of a light beam and a point on a predetermined information layer where information is to be recorded or played back. On the basis of signals from the first detector (110), a stray light detection unit (122) detects surface stray light components which are included in the signal from the position aberration detection unit (121) and which are reflected from the surface of the optical disk (108). On the basis of the detected surface stray light components, a stray light correction unit (117) corrects the signals output from the position aberration detection unit (121).