<p>A housing (25) for an optical component has holes penetrating inward, a housing body constituted of a container-like member (25A) inside of which optical components are arranged and a lid-like member (25B), and positioning members (253) for positioning the optical components at predetermined positions in the housing body. The positioning members (253) are inserted in the holes to be in contact with the optical components and position the components at predetermined positions on the axis of illumination light flux emitted from a light source.</p>
