An object of the invention is to provide a sheet alignment apparatus that is excellent in alignment properties in the conveyance direction and operates stably without being affected by various conditions, and a sheet post-processing apparatus having therein the sheet alignment apparatus. Alignment members are constructed so that alignment surfaces of the alignment members arranged to be in a form where a distance between the alignment surfaces grows greater toward the downstream side, or the direction of movement of the alignment member is made to be an oblique direction pointing to the stopper.