An image forming apparatus including: an image forming apparatus main unit; an image carrier provided in the image forming apparatus main unit; at least one developing device supported retractable from the image carrier; and a developer supply portion adapted to supply developer to the developing device, wherein: a developer inlet port provided in the developing device is slidably joined with a developer supply port provided in the developer supply portion; a seal portion is provided between the developer inlet port and the developer supply port; the seal portion includes a seal portion body made of an elastic material, a sliding portion provided on at least one of surfaces of the seal portion body, and a drawing-out portion connected to the seal portion body and to the sliding portion; and the seal portion is enabled to be drawn out by using the drawing-out portion.