A movable side regulating plate is provided on a frame body. The movable side regulating plate regulates side edges in a width direction of sheets stacked on a sheet stacking plate, and is movable in the width direction. A sheet pressing portion configured to press the side edges of the sheets and press the sheets onto a stationary side regulating plate is provided on the movable side regulating plate. The sheet pressing portion has a relief shape for reducing a pressing force exerted on the sheets when an amount of the sheets stacked on the sheet stacking plate becomes equal to or smaller than a predetermined amount. The relief shape is formed so that a downstream edge in a sheet feeding direction of a lower surface is located higher than an upstream edge in the sheet feeding direction of an upper surface.