A sheet discharging device includes a sheet discharge roller pair, a sheet discharge tray, a first actuator, a second actuator and a detector. The first actuator includes a first shaft portion and a first contact piece. The second actuator includes a second shaft portion, a second contact piece and a third contact piece. The detector detects the discharge of the sheet by the rotation of the second actuator about the second shaft portion. The leading end of a first sheet comes into contact with the first, second and third contact pieces to rotate the first and second actuators and the detector detects the discharge of the first sheet. The leading end of a second sheet comes into contact with only the third contact piece to rotate the second actuator without rotating the first actuator and the detector detects the discharge of the second sheet smaller than the first sheet.