There is provided an optical pickup compliant with a three-beam method, a phase difference method, a push-pull method and a three-beam push-pull method, comprising: an emission light source (105) for emitting two or more light components of different wavelengths; a diffraction element (107); a light collector (103); a hologram element (108); a plurality of photodetectors (206); and operation means for performing an operation on outputs of the plurality of photodetectors (206). The plurality of photodetectors (206) are at least eight photodetectors (P1 to P8) which are necessary for the execution of the three-beam method, the phase difference method, and the push-pull method. The operation means includes a switch (212) for switching between a terminal for obtaining a sub signal of the three-beam push-pull method and a terminal for obtaining a tracking signal of the three-beam method.