An image forming apparatus includes an image forming portion including a photosensitive member and a developing portion, a sheet accommodating portion, a sheet feeding portion, and a first frame. The first frame includes an upper space supporting the image forming portion, and a lower space under the upper space. A second frame is mountable to a lower portion of said first frame. The accommodating portion and the feeding portion are replaceable with a supply container containing toner to be supplied to a developing portion of the image forming portion, in which the second frame supports the accommodating portion and the feeding portion.