A tracking error signal calculating unit (221) detects a tracking error signal of light with respect to a mark recorded on a wobbled groove in a focused-on state from the light reflected back from the wobbled groove. A pull-in signal calculating unit (225) detects a total light volume signal PI of the mark, recorded on the wobbled groove, from the reflected light. A D-flipflop discriminating circuit (244) compares the phase of a binary coded version of a tracking error signal TE detected by the tracking error signal calculating unit to the phase of a binary coded version of the total light volume signal PI as detected by the pull-in signal calculating unit to discriminate the sorts of the optical discs having the same outer shape and the same optical system but differing in the UTOC recording system.