A lens array unit includes first and second lens arrays cooperative with each other. The first lens array is provided with a plurality of first convex lenses and a first transparent holder formed integral with the first lenses. Each of the first lenses has first and second lens surfaces. The second lens array is provided with a plurality of second convex lenses and a second transparent holder formed integral with the second lenses Each of the second lenses has third and fourth lens surfaces. The second lens array is attached to the first lens array so that the third lens surfaces face the second lens surfaces. The lens array unit further includes a light shield mounted on the first lens array. The light shield is formed with a plurality of through-holes each facing the relevant one of the first lens surfaces.