An image reading device and an image forming apparatus and methods thereof can achieve a duplex scanning operation and enable a user to easily arrange the scanned documents after being discharged. The image reading device may include a supply path coupled to a document supply port, a simplex document feeding path coupled to the supply path to first guide the document to the scan unit, a duplex document feeding path coupled to the supply path to second guide the document to the scan unit to scan a first surface of the document, and a duplex document circulating path to communicate with the duplex document feeding path and guide a second surface of the first surface scanned document to the scan unit.