To easily insert a form plate into a front edge clamping device by preparing the plate, loading a front region of the plate to insert the plate into the device to mount the plate at a plate cylinder, and forming a bend directed to insert a front edge of the plate substantially parallel to a clamping surface of the device.

At a position where a form plate 2 is guided into a front edge clamping device 5, a front edge 7 of the plate 2 is held at an introducing roller 14, and the roller 14 tends to ride to slide on an upper surface of a clamping jaw 13 of an upper side by a reverse rotation 9 of a plate cylinder 4. To stop this trend, a form plate bending roller 12 is provided. A load is given to the edge 7 of the plate 2 by a regulating motion of the roller indicated by an arrow 24, and a bend 6 is formed at the late 2. That is, the edge 7 of the plate 2 is directed parallel to a clamping surface 8 of the device 5 to be slidable between clamping jaws 13 without engaging, and the plate 2 is easily and effectively inserted into the device 5.