An image reading device, which can be included in an image forming apparatus, includes an image pickup device, a transparent member, a traveling body, and a housing. The traveling body includes a light source to emit light and guides the light reflected from a surface of the document to the image pickup device while moving in a sub scanning direction along the document surface on the transparent member. The housing accommodates the image pickup device and the traveling body, and includes a base member including a rectangular bottom surface and a side surface, and a rail member including a rail surface and a first vertical surface. The rail member further includes a fixing part that is a surface to be fixed to the bottom surface of the base member and to extend from one end of the rail member in the sub scanning direction to the other end.