Patent ID: 7428201

Claim:
An optical disc apparatus having an optical pick-up that applies an optical beam to an optical disc on which one or more information recording layers are laminated in the direction of thickness through an objective lens and detects a reflected light from one of the information recording layers laminated on the optical disc, said optical disc apparatus comprising: a photodetecting unit having a first photodetecting part for detecting the reflected light from the one information recording layer and a second photodetecting part composed of one or more light receiving surfaces for detecting whether or not there is a stray light from other information recording layers and the quantity of light thereof; and a control unit for discriminating the number of the information recording layers laminated on the optical disc on the basis of the intensity of the stray light and/or the distribution of the intensity detected by the second photodetecting part in the photodetecting unit and changing the setting of the optical pick-up in accordance with the discriminated number of the information recording layers, wherein the control unit discriminates the kind of the optical disc on the basis of the presence or absence of the stray light from other information recording layers detected by the second photodetecting part in the photodetecting unit and the quantity of light thereof.