Sheet processing apparatus and image forming apparatus equipped with same

A sheet processing apparatus comprising:

• sheet holding means for holding a plurality of supplied sheets in a stack;
• first sheet stacking means on which sheets that have been held by said sheet holding means or have passed through said sheet holding means without being held are stacked and subjected to a processing;
• second sheet stacking means, provided downstream of said first sheet stacking means with respect to a sheet conveying direction, on which sheets are to be stacked;
• first sheet conveying means for conveying said sheets stacked on said first sheet stacking means to discharge the sheets to said second sheet stacking means;
• and
• second sheet conveying means for conveying said sheets stacked on said first sheet stacking means toward said second sheet stacking means;
• wherein after the sheets stacked on said first sheet stacking means are conveyed by said second sheet conveying means toward said second sheet stacking means by a predetermined amount, said first sheet conveying means conveys the sheets held by said sheet holding means and the sheets stacked on said first sheet stacking means simultaneously under a state in which a downstream edge of the sheet stacked on said first sheet stacking means protrudes in a downstream side beyond a downstream edge of the sheets held by said sheet holding means by a predetermined amount to thereby discharge the sheets stacked on said first sheet stacking means to said second sheet stacking means and to stack the sheets held by said sheet holding means onto said first sheet stacking means.