Sheet stacking apparatus and image forming apparatus

An image forming apparatus, comprising:

• a sheet stacking apparatus, including:
• a sheet stacking unit configured to stack a sheet thereon;
• and
• a sheet regulating unit movable with respect to the sheet stacking unit, and
• an image formation unit configured to form an image on a sheet fed from the sheet stacking apparatus,
• the sheet regulating unit including:
• a main body having a regulating surface which is brought into abutment against an edge of the sheet stacked on the sheet stacking unit to regulate a position of the sheet;
• and
• an operating portion having a pressable pressure surface, moved from a first position to a second position by pressing the pressure surface, and pivotably supported on the main body about a pivoting fulcrum positioned above a middle position of the pressure surface, the main body being regulated from moving with respect to the sheet stacking unit when the operating portion is in the first position, and the main body being allowed to move with respect to the sheet stacking unit when the operating portion is in the second position,
• wherein the operating portion moves from the first position to the second position by pressing the pressure surface in a direction away from the edge of the sheet to be regulated by the regulating surface.