A sheet post-processing device includes a conveying section that conveys a paper sheet; a punch section that punches punch holes in the paper sheet conveyed by the conveying section; a stacker section that stores the paper sheet in which the punch holes are punched by the punch section; a binding section that binds a paper sheet bundle stored in the stacker section with a binding member; and a controller that controls the above sections. The controller selectively performs a ring binding mode and a direct binding mode. The ring binding mode is a mode in which punch holes are punched in the paper sheet by the punch section and then the binding member is made to penetrate the punch holes for binding. The direct binding mode is a mode in which the binding member is directly driven into the paper sheet bundle without punching the punch holes in the sheet.