A sheet post-processing apparatus includes a first stapler and a second stapler having different thicknesses of sheets on which a binding process can be performed. A control unit can perform a manual staple mode. If the first stapler is selected as a stapler for performing the binding process in the manual staple mode, the control unit controls the alignment member moving mechanism to move alignment members to a position defining a first insertion position for guiding the sheets to a first placing position. If the second stapler is selected, the control unit controls the alignment member moving mechanism to move the alignment members to a position defining a second insertion position for guiding the sheets to a second placing position.