Paper finisher having paper perforating apparatus, and image forming apparatus equipped with paper perforating apparatus and paper finisher

A paper perforating apparatus which can securely prevent a paper end portion from being caught in a punch hole, without having an assist member, such as mylar, in a paper finisher which comprises a perforating device capable of moving in a direction perpendicular to the paper conveyance direction, the paper perforating apparatus, comprising: a paper conveyance device for conveying a paper; a perforating device for perforating the paper; a paper end portion detecting device for detecting an end portion parallel to the conveyance direction of the paper; and a device for moving the perforating device in a direction perpendicular to the conveyance direction, wherein the paper perforating apparatus offsets a standby position of the perforating device, which is in the direction perpendicular to the paper conveyance direction, from a position in which holes are punched out on the paper by a predetermined distance, and the perforating device starts operation of perforation preparation from the standby position after being passed by a front end of the paper.