An image reading apparatus and an image forming apparatus including the same to improve a transferring path of a document to prevent curl from being generated in the document and to prevent interference between a document having both surfaces scanned and a previously discharged document. The image reading apparatus includes a scan path having one end connected to a document supplying unit and the other end connected to a document discharging unit, a scan unit to read information recorded on a document passing through the scan path, a two-sided document branch path to branch from the scan path so that the document whose first surface is scanned by the scan unit passes through the two-sided document branch path before the document is reversed for a two-side scanning process, and a two-sided document transferring path having one end connected to the two-sided document branch path and other end connected to the scan path. A two-sided document guide is provided between the document supplying unit and the document discharging unit in a vertical direction to guide the document discharged from the two-sided document branch path.