are then retried at the lowest cav speed adjusted by the controller 201 2 operation 306 2 next it is determined whether data detection data buffering and data decoding were performed successfully operation 306 3 in a case where data detection data buffering and data decoding are performed successfully at the lowest cav speed the process proceeds to operation 304 in the case where data detection data buffering or data decoding fail at the lowest cav speed the rom driver 201 retries data detection data buffering and data decoding while reducing an offset between the target location and a reference location operation 306 4 the retry count is counted by the counter 203 3 the retry count can be set by the controller 201 2 if data detection data buffering and data decoding are performed successfully before the retry count is terminated the process proceeds to operation 304 if data detection data buffering or data decoding is not performed successfully until the retry count is terminated the process proceeds to operation 307 operation 306 5 returning to fig2 and 3 if data detection data buffering or data decoding fail due to certain defects on the optical disc 201 1 after the controller 201 2 controls the meca driver 201 4 so the optical pick up 201 5 is moved.