A sheets processing apparatus includes a first processing portion having a first switchback portion for reversing the conveying direction of postal matter branched and conveyed from a main conveying path and a first U-turn path for reversing the front and back of the postal matter and a second processing portion having a second U-turn path for reversing the front and back of the postal matter branched and conveyed from the main conveying path and a second switchback portion for reversing the conveying direction of the postal matter. The first switchback portion is arranged inside the second U-turn path and the second switchback portion is arranged inside the first U-turn path.