An erecting equal-
magnification lens array plate includes a stack of a plurality
lens array plates built such that pairs of corresponding lenses form a coaxial lens
system, where each
lens array plate is formed with a plurality of convex lenses on both surfaces of the plate. The plate receives light from a substantially straight
light source facing one side of the plate, and the plate forms an erect equal-
magnification image of the substantially straight
light source on an
image plane facing the other side of the plate. The main lens arrangement direction differs from the main scanning direction of the erecting equal-
magnification lens array plate. The erecting equal-magnification lens array plate is provided with a
first light shielding member operative to shield light not contributing to imaging and formed in the neighborhood of a position in the intermediate plane in the erecting equal-magnification lens array plate where an inverted image of the substantially straight
light source is formed, and with a second light shielding member operative to reduce the amount of light incident on at least some of the lenses at the periphery in the sub-scanning direction and provided on a lens surface facing a light source.