A sheet stacking apparatus includes a lowering control unit, a determination unit, a notification unit, and a control unit. The lowering control unit lowers a discharge tray based on an amount of sheets discharged to the tray. The determination unit can determine that lowering of the discharge tray has been disabled before the discharge tray reaches a lower end position. The notification unit notifies removal of an object present below the discharge tray when it is determined that the lowering of the discharge tray has been disabled. The control unit executes control so as to raise the discharge tray in response to the determination that the lowering of the discharge tray has been disabled.