An optical pickup apparatus which supports two wavelengths and is amenable to a reduction in size without employing a combining prism. The optical pickup apparatus employs a semiconductor laser device implemented in the form of a one-chip laser diode having two light sources for emitting a first laser beam and a second laser beam at a wavelength different from that of the first laser beam. A photodetector unit has a first detector section for receiving the first laser beam and a second detector section for receiving the second laser beam, and is set at positions at which the first and second laser beams follow return light paths of different lengths from an optical disc to the first and second detector sections.