PURPOSE: To guide the leading end of plate material smoothly and prevent the occurence of bending caused by collision of the leading end part against a roll 3 in conventional methods by providing the pressure metal of the specific shape in the specific place, in a plate material bender passed between three rolls.

CONSTITUTION: In passing a plate material P between three rolls 1, 2, 3 to bend the same to a fixed curvature, a pressure metal 4 is provided between the rollers 2, 3. The pressure metal 4 has a spring 9 making contact to the bottom end of a vertically movable support base 5 and its bottom end is formed to a concave face having the curvature close to that of the outside circumference of the roll 1 so as to be able to engage with the roll 1. Grooves are porvided in both surfaces of the lower part so as to prevent the portions of a larger diameter of the rolls 2, 3 do not contact. The movement of the pressure metal downward is limited by a stopper 8. After the pressure metal 4 is contacted to the plate material by lowering the support base 5, it is pressed by the roll 2 under specified pressure and therefore its entry between the rolls 1, 3 smoothly accomplished and bending is prevented.