Abstract: A disk discrimination method for a digital versatile disk (DVD) system uses a sum signal and a focus error signal as a difference signal obtained from the amount of light detected from divided optical detection areas of a divided-by-eight photodiode in a loaded disk, to discriminate whether a loaded disk is a DVD or compact disk (CD). When offsets of the sum signal and the focus error signal are normal, and are larger than predetermined reference signals, it is judged that the loaded disk is a DVD, while the loaded disk is judged to be a CD when the sum signal and the focus error signal are smaller than the reference signals. When disk type discrimination fails, an optical pickup moves a predetermined number of times to retry discrimination. Such discrimination method increases reliability of the discrimination results.