An adhesive tape inserted into a tape inserting clearance defined between a tape supplying roller and a tape guide is supplied to joining rollers while being wound around the tape supplying roller under guidance. At the tape inserting clearance, one side edge of the adhesive tape is guided to a tape positioner in slide contact, to be positioned in a tape width direction, and further, the adhesive tape T is inserted and moved while allowing the tape to be moved toward the other side edge of the adhesive tape.