A sheet finishing apparatus includes a first conveyance path connected to a sheet conveyance inlet, a second conveyance path branching from the first conveyance path, a folding roller device disposed in the second conveyance path for folding the sheet, and a sheet discharge path arranged vertically parallel to the second conveyance path and guiding the folded sheet from the second conveyance path to a sheet conveyance outlet. The second conveyance path includes a first guide path located at a downstream side relative to the folding roller device and guiding a rear side of the sheet, and a second guide path located at an upstream side relative to the folding roller device and guiding a front side of the folded sheet conveyed from the folding roller device. A gate is formed for selectively guiding the folded sheet from the second guide path to the storage device or the sheet discharge path.