The present invention relates to a device of regulating a running position of unsealing tape for packing film, in which in the normal operation unsealing tape runs on a linear normal running position disposed between projecting portions and by being guided by the projecting portions and while being in contact therewith, if the unsealing tape runs on the outside of an annular groove by being shifted to either side in the width direction, as a result of a relative movement of the annular groove in the direction reverse to the rotational direction of the regulating roller with the rotation of the regulating roller, the unsealing tape gradually enters the annular groove by being guided by corner portions and on the side of openings produced by separating portions and while being in an abrasive contact therewith, thereafter, the unsealing tape is drawn to the normal running position by being guided by approaching portions and while being in contact therewith and finally the unsealing tape is returned to the normal running position by being brought into contact with the projecting portions.