To improve optical performance of an erecting life-size lens array alate.

An erecting life-size lens array plate 11 includes a first lens array plate 24, a second lens array plate 26, a first light-shielding member, a second light-shielding member, and an intermediate light-shielding member. The first light-shielding member, the second light-shielding member, and the intermediate light-shielding member are divided into two parts on a division surface that is parallel to a main scanning direction. The divided one first divided light-shielding member 31a, one second divided light-shielding member 32a and one intermediate divided light-shielding member 33a are integrated together to constitute a first divided holder 30a. The divided other first divided light-shielding member 31b, the other second divided light-shielding member 32b, and the other intermediate divided light-shielding member 33b are integrated together to constitute a second divided holder 30b. The erecting life-size lens array plate 11 is assembled by clamping the first lens array plate 24 and the second lens array plate 26 between the first divided holder 30a and the second divided holder 30b.