PURPOSE: To prevent the breakage of a molded article by detecting the position of a molded article individually clamped by the upper and lower-side floating clamp units and cutting a weir by a cutter.

CONSTITUTION: After a work 4 is set onto a work main clamp unit 5, a starting switch is turned-ON to clamp the both edges of the work. Then, an upper-side floating clamp unit 6 is lowered to individually clamp the molded article 4a of the work 4 between a lower-side floating clamp unit 7, and a position detector 8 is advanced, and a detection arm 17 is turned to the work 4 side by the detection-ON signal, and a feed unit 12 is transferred. At this time, the detection arm 17 contacts with the edge surface of the molded article 4a, and a spline shaft is brought into stop, and an adjusting bolt and the contactor of the detector contact each other, and the unit 12 is brought into stop, and then the bolt and the detector are separated, and a cutter 21 cuts the molded article to form a weir 4b.