A first folding portion includes: a first folding roller pair consisting of a common roller and a first roller; and a blade member that feeds a sheet to a first nip, thereby forming a first fold on the sheet in the first nip. A second folding portion includes a second folding roller pair consisting of the common roller and a second roller, thereby forming a second fold on the sheet in a second nip. The common roller and the first roller are parallel in a conveying direction in a case where the sheet is guided toward the first folding portion. A feeding portion evacuates the sheet to the evacuation guiding portion for evacuating the sheet that on which the first fold is formed, switches back the sheet, and then feeds the sheet into the second nip.