Abstract: Tearing device for the tearing off of a band (26) in a desired point provided with a zone (90) arranged to make the tearing easier, such as a weakening by means of perforations or slits provided along a predetermined line, comprising at least a first pair of opposed and perfectly cylindrical rollers (30,32) driven at a first rotation rate, and at least a second pair of opposed rollers (50,52), each having at least a planar bevel (54,56), the second roller pair being positioned downstream with respect to the first pair and being normally stationary with the bevels facing each other, the rollers (54,56) of the second pair being driven, upon receiving a command signal coming from a detector (74) at a rotation rate definitely higher than that of the first pair of rollers, thus causing the band to be torn in the desired zone.