An image forming apparatus includes an image forming unit configured to form an image on a sheet, and a re-feeding mechanism configured to re-feed the sheet to the image forming unit. The re-feeding mechanism includes a fixed guide configured to guide the sheet fed in a sheet feed direction and having a guide surface partially defining re-feeding path through which the sheet passes, a base guide disposed downstream of the fixed guide, and a movable guide having a guide surface and configured to guide the sheet guided by the fixed guide and to move toward and away from the base guide. The fixed guide includes an engaging portion and the movable guide includes an engaging portion. The guide surface of the movable guide is positioned relative to the guide surface of the fixed guide when the engaging portion of the movable guide engages the engaging portion of the fixed guide.