Optical pickup device, optical disc device and prism

An optical pickup device includes: a light source; a collimator lens for converting a light beam emitted from the light source into parallel light; an objective lens for converging the light beam to the optical disc; an extending portion in which a light flux transversal width as the width of the parallel direction with respect to the information recording face of the optical disc of the light beam converted into the parallel light by the collimator lens is extended until a final light flux diameter as the diameter of the light beam at an incident time to the objective lens; and a prism in which a light flux longitudinal width as the width of a direction perpendicular to the information recording face of the optical disc of the extended light beam is extended until the final light flux diameter, and the light beam is emitted to the objective lens.