A sheet finisher for executing preselected processing with a sheet conveyed thereto of the present invention includes a first processing tray configured to temporarily store the sheet and deliver it. A first and a second path are positioned downstream of the first processing tray in a direction of sheet conveyance and configured to convey a first and a second sheet stack, respectively. The first path conveys the first sheet stack upward over the downstream portion of the first processing tray while the second path conveys it downward over the same. A switching device selects either one of the first and second paths. The sheet finisher of the present invention is low cost and highly productive and space saving.