An image forming apparatus includes a discharge rollers pair, a sheet pressing member and a discharge tray. The sheet pressing member includes a first rotational shaft, a detection piece and a corrugation piece. The corrugation piece protrudes in a radial direction different from a protruding direction of the detection piece from the first rotational shaft. When the detection piece is turned at a first angle into a first posture, the corrugation piece is changed into a contact posture where the corrugation piece comes into contact with the sheet to apply stiffness on the sheet. When the detection piece is turned at a second angle into a second posture, the corrugation piece is changed into a retracting posture where the corrugation piece separates from the sheet.