An objective lens holder of the present invention includes: (i) a cavity, having an entrance and an exit, which guides, to an objective lens, an incident light beam entering the entrance, the exit being provided on a side of the cavity where the objective lens is housed; and (ii) an aperture having an opening for limiting, to an effective diameter of the objective lens, a beam diameter of the incident light beam passing through the cavity. The cavity is surrounded with internal wall surfaces facing each other so that space between the internal wall surfaces gradually increases from the opening of the aperture toward the entrance or the exit. This makes it possible to provide a highly rigid objective lens holder that allows high speed read/write operations.