An optical pickup wherein a main beam and at least two sub-beams are collected on a disc and a tracking error signal is detected from push pull signals generated from each beam. A phase of the push pull signal generated from the first sub-beam is shifted from a phase of the push pull signal generated from the second sub-beam by substantially 180°. A phase difference is given to a part of the first sub-beam (10) and a part of the second sub-beam (11) by a diffraction optical element (2) which generates the first sub-beam (10) and the second sub-beam (11).