The image forming apparatus includes a chassis of a main body of the image forming apparatus, an image bearing member unit; a roller unit, and a first image bearing member supporting member, wherein the image bearing member unit includes, a chassis; and a second image bearing member supporting member, and wherein the roller unit includes a chassis; a first roller supporting member, a second roller supporting member, a first roller unit positioning member; and a second roller unit positioning member that comes into contact with a member provided at a predetermined position on the chassis of the image bearing member unit. This improves position accuracy of a roller with respect to an image bearing member, and prevents generation of a defective image.