A lens array unit includes first lens array plates, second lens array plates and a support member. Each of the first lens array plate has multiple first lenses thereon. Each of the first lenses has a first optical axis that extends in a first direction and the first lenses are arranged in a second direction perpendicular to the first. Each of the second lens array plates has multiple second lenses thereon. Each of the second lenses has a second optical axis that extends in the first direction and the second lenses are arranged in the second. The support member has opposite first and second sides. The support member extends in the second direction to support the first lens array plates on the first side and support the second lens array plates on a second side so that each of the first lens array plates opposes a different corresponding one of the second lens array plates. The first lens array plates are arranged on the first side of the support member in the second direction and the second lens array plates are arranged on the second side of the support member in the second direction.