An image forming apparatus includes an image forming unit (101) configured to form an image on a sheet (S), a stacking portion (106) on which the sheet having the image formed thereon is to be stacked, a first roller (361) capable of forward and reverse rotations, a second roller (351) capable of rotating with the first roller when the first roller makes a forward rotation, a third roller (371) capable of rotating with the first roller when the first roller makes a reverse rotation and then the forward rotation, a regulation portion (425) movable between a regulation position where entering of the sheet into a nip portion between the first and second rollers is prevented, and an allowing position where discharge of the sheet is allowed, and a movement unit (90) configured to cause the regulation portion to be placed in the allowing position during forward rotation, and to be placed in the regulation position during reverse rotation.