Abstract: The object of the present invention is to provide a low-priced automatized weight control device for filter-rods, able to be easily installed in present manufacturing facilities and to be operated easily without any need of special equipment or special operating qualifications.The automatized weight-control device is comprised of a tension gauge measuring the tension in the tow in the first processing step of the tow manufacturing process, and a weight control system to regulate the second processing step to keep the tension in the tow at the specified constant value by increasing the speed of the pretension rollers through the microcomputer by applying the signals transmitted from the tension gauge.