Provided are a sheet pressing mechanism which can suppress the middle folding of the sheet when the discharged sheet comes into contact with the pressing member, thereby being capable of effectively preventing the sheet from being stacked on the discharge tray in a state that the front end is bent downward, and an image forming apparatus.The sheet pressing mechanism includes a pressing member configured to press a sheet that has been deformed to corrugate in a width direction that is orthogonal to a sheet discharging direction when the sheet is discharged toward a discharge tray. The pressingmember has a first pressing area for pressing portions other than a top portion of a crest of the sheet when the discharged sheet comes into contact with the pressing member.