Sheet stacking apparatus with stacking and retaining tray

摘要

A sheet stacking apparatus includes a sheet discharging device for discharging sheets; a stacking tray for stacking sets of the sheets discharged by the sheet discharging device; a retaining tray for retaining one sheet discharging by the discharging device; a shifting device for shifting, in a direction crossing with a direction of the discharging of the sheet, the one sheet on the retaining tray; a feeding device for feeding the one sheet to the stacking tray; whereby the sets of the sheets are grouped with the sheet shifted by the shifting device.