An image forming apparatus including an image forming unit to form an image on a print medium, the image forming apparatus including a guide shaft, first and second shaft insertion members into which the guide shaft is inserted, a unit main body including first and second insertion holes provided along the guide shaft and whose diameters larger than external diameters of the first and second shaft insertion members, respectively, and an adhesive to adhere the first and second shaft insertion members inserted into the first and second insertion holes, to the unit main body.