An objective lens causes light emitted from the light source to converged onto an optical recording medium. A beam splitter separates light, reflected from the optical recording medium, from the bundle of rays emitted from the light source. A detective lens causes the light separated by means of the beam splitter to be converged. A detective photosensitive element is disposed at a position at which the light converged by means of the detective lens approximately converges. The detective lens has a first and second surfaces. The first surface faces the beam splitter and is formed to be convex so as to cause the bundle of rays to converge. The second surface comprises two surfaces which are combined with one another so that the line of intersection, formed where the two surfaces meet, does not intersect the axis associated with the convexity of the first surface.