An optical pickup apparatus and an optical disc apparatus are adapted to raise the efficiency of utilization of the lasers of the apparatus for accurately detecting tracking errors by raising the intensity ratio of the beam of the 0-th order to the beams of the ±1st orders produced by splitting of the laser beam of the wavelength to be subjected to division by three. The optical pickup apparatus includes a light emitting section for emitting a first laser beam having wavelength λ1 and a second laser beam having wavelength λ2 different from the wavelength λ1, a surface relief type first diffraction grating having a phase height of two steps produced by being equipped with a first phase grating and a second phase grating arranged at opposite sides of the first phase grating and adapted to split the laser beam of the wavelength λ1 into three beams and transmit substantially all of the laser beam of the wavelength λ2, a surface relief type second diffraction grating having a phase height of two steps produced by being equipped with a first phase grating and a second phase grating arranged at opposite sides of the first phase grating and adapted to split the laser beam of the wavelength λ2 into three beams and transmit substantially all of the laser beam of the wavelength λ1, an objective lens for converging the laser beams emitted from the light emitting section onto an optical disc, an optical element for branching the optical paths of return light reflected by the optical disc, and a light receiving section for receiving the return light branched by the optical element.