In order to provide a sheet stacking apparatus for maintaining alignment characteristics of long-length sheets, the sheet stacking apparatus is a sheet stacking apparatus located above in a pair of sheet stacking apparatuses provided to overlap vertically along a vertical direction, and is provided with a first stacking section for stacking sheets, a second stacking section provided to extend from a downstream end of the first stacking section in a sheet transport direction and connected to the first stacking section rotatably, and a third stacking section which is attached to the second stacking section to extend from a downstream end of the second stacking section in the sheet transport direction, includes an inclined angle with respect to a horizontal surface smaller than in the second placing face, and which is attachable and detachable with respect to the second stacking section in a rotation direction.