A switchback mechanism for reversing a mail item conveying direction has a switchback roller which holds the mail item in a nip and rotates in both forward and backward directions. When there is a remaining mail item deviated from the nip of the switchback roller and remaining in the switchback unit, a pressure roller is pressed to an output roller always rotating in the direction of R1, the remaining mail item is held and fed out to the nip. At this time, a control unit takes out the remaining mail item at timing not to interfere with other mail items.