The present invention provides an image forming apparatus with a supply roller for supplying a sheet, a supply path for directing the sheet to an image forming section, a sheet ejecting path for the sheet on which an image is formed at the image forming section toward an ejecting section, a space integrally formed in a lower part of a body of the image forming apparatus, a branch path branched from the sheet ejecting path and adapted to direct the sheet toward the space, an introduction path for directing the sheet from the space to the supply path, and a sheet re-feeing unit removable with respect to the body of the image forming apparatus and including a sheet re-feeding path having an entrance facing the branch path and an exit facing the introduction path.