An image forming apparatus includes a body frame, a drum unit, and an exposure unit. The drum unit is inserted to between a pair of side plates through an opening. The body frame includes a fitted plate. The drum unit is fitted to, in a state positioned with respect to, the fitted plate. The exposure unit is fitted to, in a state positioned with respect to, a stay. One side plate has a through hole. The stay has a positioning protrusion. The fitted plate has a positioning hole. Inserting the positioning projection that projects outward from the one side plate through the through hole into the positioning hole positions the stay and the fitted plate with respect to each other.