PROBLEM TO BE SOLVED: To provide a sheet process device allowing few occurrence of misalignment or feed-out failure.SOLUTION: A sheet process device includes: a process tray for stacking a sheet constituting a processing target; a stacking tray, disposed in front of the process tray, for receiving and stacking a post-process sheet fed out from the process tray; and a curl suppression plate that is extended substantially parallel with the process tray and apart therefrom with a predetermined gap so as to cover a partial zone of the process tray on the feed-out-side and suppresses a curl of the post-process sheet fed from the process tray to the stacking tray.