Tray means for stacking sheets, pickup means for separating and for conveying sheets into a single sheet on the tray means, and sheet conveyance means for conveying a sheet separated by the pickup means to a predetermined processing position are provided. Projecting guide means project from a sheet support surface of the tray means into a notched opening of the sheet is provided; and an oblique surface is formed to prevent a trailing side edge of the opening from catching on a leading side edge of the opening of a lower sheet when feeding an uppermost sheet to the projecting guide means. This makes it possible to feed only the uppermost sheet downstream without an opening edge formed in the uppermost sheet from interfering with an opening edge of a lower sheet.