Abstract: An image forming apparatus having a receiving unit for receiving a sheet on which a first image is formed. The receiving unit includes an inlet for receiving the sheet, a tray member for supporting the received sheet, an outlet through which the received sheet is re-fed, and an aligning device. The aligning device includes a pair of standing members positioned on the tray member in spaced relationship with each other a predetermined distance. The standing members extend upward to a level which is higher than the inlet. And at least one of the pair of standing members has a widened portion for guiding the sheet passing through the sheet inlet. The sheet is guided by the widened portion and aligned on the tray member by the pair of standing members and the sheet is re-fed out of the tray member to form a second image.