A sheet processing apparatus includes: a stacking unit that stacks conveyed sheets; an aligning unit that aligns the sheets stacked on the stacking unit in a sheet conveying direction; a binding unit that moves along an end portion of a bundle of the sheets on a binding portion side and performs a binding process for the bundle of the sheets that have been aligned by the aligning unit; a pressing unit that presses the bundle of the sheets at the end portion thereof on the binding portion side; and an interlocking unit that moves the pressing unit in association with a motion of the binding unit.