A sheet stacking apparatus including first and second stacking trays configured to stack sheets, a detection unit configured to detect a sheet stacking amount on the first stacking tray, a setting unit configured to set an upper limit on stacking amount for controlling the sheet stacking amount that is less than a maximum sheet stacking amount on the first stacking tray, and a control unit configured to stop stacking of sheets on the first stacking tray and stack sheets on the second stacking tray in a case where the sheet stacking amount which is detected by the detection unit reaches the upper limit on stacking amount that is set by the setting unit.