An image forming apparatus includes an image carrier unit, a developing unit, a supporting frame, a retainer and a sheet member. The image carrier unit includes an image carrier on which an electrostatic latent image is formed. The developing unit develops the electrostatic latent image with toner. The supporting frame supports the image carrier unit and the developing unit in an attachable and detachable manner. The retainer is supported by the supporting frame in a turnable manner, and positions the image carrier unit and the developing unit to the supporting frame by being turned upward. The sheet member closes a gap between the supporting frame and the retainer. The sheet member has an upper section supported by the retainer and a lower end section supported by the supporting frame, and at least one of the upper end section and the lower end section is configured to be detachable.