A sheet sorting device having a plurality of bins arranged vertically for accommodating sheets transported by a sheet transporting device and a sheet adjusting member provided in a vertical direction with respect to the sheet transporting device. One of the bins which faces a sheet aligning member is slid horizontally thereto by a moving mechanism so as to align a sheet accommodated in each bin by the sheet aligning member by pushing the sheet to an aligning reference portion formed by adjacent two sides of each bin. The sheet sorting device further has a stapler in the vicinity of the sheet aligning member to staple the sheets aligned by the sheet aligning member. At least either the bins or the aligning member and sheet transporting device is capable of being elevated up and down so as to transport sheets to each bin by the sheet transport device while the sheet aligning member aligns the sheet transported to the bin one by one.