A lens unit includes a lens holder of stainless steel and a converging lens fixed to a lens holding hole of the lens holder. The lens holder is formed by pressing, or stamping from a metal plate, made of a compressed stainless steel plate material, having a predetermined thickness with a narrow tolerance. Upon stamping, the metal plate is fractured, thus forming an outer tapered surface at one end of the outer surface of the lens holder. When the outer surface and the rear end surface of the lens holder are allowed to abut against a positioning recess in order to position the lens holder, the outer tapered surface is opposed to the corner of the positioning recess.