An erecting equal-magnification lens array plate includes: first and second lens array plates; first, second and intermediate light shielding member. The first, second and intermediate light shielding member are halved by a splitting plane parallel with the main scanning direction. One of the first light shielding member pieces, one of the second light shielding member pieces, and one of the intermediate light shielding member pieces produced by halving the members are integrated to form a first holder piece. The other of the first light shielding member pieces, the other of the second light shielding member pieces, and the other of the intermediate light shielding member pieces produced by halving the members are integrated to form a second holder piece. The erecting equal-magnification lens array plate is assembled by sandwiching the first lens array plate and the second lens array plate by the first holder piece and the second holder piece.