A sheet output apparatus includes a sheet set generating unit, an information obtaining unit, a decision unit, an output unit, and a control unit. The sheet set generating unit generates a set of sheets by stapling plural sheets. The information obtaining unit obtains image forming information with respect to each of the plural sheets constituting the set of sheets. The decision unit decides whether a pair of sheets including two sheets in which the images formed on the sheets face each other exists or not in the plural sheets. The output unit comes into contact with at least one of the uppermost sheet and the lowermost sheet in the set of sheets to apply a force to the sheet, and outputs the set of sheets in the output direction. The control unit controls the output unit to output the set of sheets.