Exposure device and image forming apparatus

An exposure device comprising:

• a first lens array unit and a second lens array unit each including a plurality of optical elements formed in a formation surface with respective optical axes parallel to each other, the formation surface of the first lens army unit being not perpendicular to the optical axes;
• a first lens array holder and a second lens array holder that hold the first lens array unit and the second lens array unit with the respective optical axes of the plurality of optical elements parallel to each other;
• and
• a light source assembly in which optical element groups each including a plurality of light-emitting devices aligned in a direction perpendicular to the optical axes are disposed at different positions in a direction parallel to the optical axes,
• wherein the first lens array unit is provided with a first seating surface on which the first lens array holder abuts and a second seating surface on which the second lens array holder abuts, on a surface facing the second lens array unit, and
• the first seating surface and the second seating surface are perpendicular to the optical axes.