An optical information recording and reproducing apparatus, an optical information recording and reproducing method, and a data library apparatus which make it possible to conduct alternation processing efficiently even if a buffer capacity is limited, in retry processing at time when a verify error is detected are provided. In the optical information recording and reproducing apparatus for recording data onto optical information recording media and reproducing data from the optical information recording media, verify processing is conducted in a predetermined recording quantity unit. Upon detection of a verify error in recorded data, a host computer is requested to retransfer data which has caused the verify error, and received data is intruded in a next scheduled recording quantity unit and recorded onto the optical information recording media.