A peeling device according to one aspect of the invention peels off part of a peel-off paper from a peel-off paper-backed adhesive tape which is a laminate of a substrate tape having a surface coated with an adhesive and a peel-off paper affixed to the substrate tape via the adhesive. A rotational member is rotated by a driving force transmitted from a drive source. On an end face of the rotational member there are arranged a peeling projection rotated to be brought into contact with a substrate tape-side surface of an end of the peel-off paper-backed adhesive tape to carry out a bending releasing action on said end portion of the adhesive tape. The adhesive tape is guided toward the peeling projection when it is inserted and part of the end portion other than a free end brought to the peeling projection is held. In a tape processing device for processing a peel-off paper-backed adhesive tape, according to another aspect of the invention, a trimming mechanism trims one end of the peel-off paper-backed adhesive tape, while a peeling mechanism peels off a peel-off paper from the peel-off paper-backed adhesive tape. The driving force is transmitted to the trimming mechanism and the peeling mechanism from a simple drive force. There is also provided a tape printing apparatus incorporating the tape processing device.