Apparatus for optically recording and reproducing information

An apparatus for optically recording and reproducing information in and from an optical information recording medium having a guide track. The apparatus uses an optical head having a diffraction grating, for recording and reproducing information. In recording information, a zero-order diffraction light beam from the diffraction grating is used for the information recording, and plus/minus first-order diffraction light beams from the diffraction grating are used for the tracking. In reproducing information, the zero-order diffraction light beam is used for the tracking, and higher- and odd-order diffraction light beams including at least plus/minus first-order diffraction light beams are used for information reproduction.