An optical pickup includes at least a laser light source emitting a laser
beam, a collimator lens system including a plurality of lenses for
collimating the light beam emitted from the laser light source and
incident thereupon as diffused light, and an objective lens. The laser
beam transmitted through the collimator lens system is incident upon the
objective lens. The collimator lens system includes a first lens unit
held so as to be movable in an optical axis direction of the laser beam
and a fixed second lens unit.