A defect detection circuit for optical pick up device having a record medium on which a track is formed which track has a plurality of segments formed in series along the track. The circuit comprises a first detection circuit for detecting a defect of a segment sampled to be detected by comparing difference between a latest data of a refresh signal from the segment and a preceding data of a refresh signal from a preceding segment sampled before the segment to be detected with a first predetermined value. The circuit further comprises a second detection circuit for detecting a defect of the segment to be detected by comparing the latest data with a second predetermined value and a discrimination circuit for discriminating whether the segment is defective or not.