Abstract: A sheet aligning apparatus for a copying machine having a loading unit capable of loading a plurality of stacked sheets. A comparing unit determines and compares respective sizes of at least two sheets partially stacked and loaded on the loading unit. An alignment unit carries out alignment when the width of a sheet of a first job is the same or smaller than a sheet of a second job and inhibits carrying out alignment when the width of a sheet of the first job is greater than a sheet of the second job. The apparatus further includes first and second discharge units for discharging a group of sheets from respective first and second jobs onto the load unit. A determination unit determines successiveness of the first and second jobs and, based on a result of the determination, a post-processing unit executes post-processing for the group of sheets of the first job upon completion of discharging the group of sheets of the second job.