PURPOSE: To form an extrusion part on a plate stock and to save the manufacturing cost of a die, die changing time, etc., by extruding one part on the surface of a plate stock in pressurizing direction by pressing with the outer peripheral face of a roller and moving one part of the plate stock and the roller.

CONSTITUTION: A roller 14 and rollers 15a, 15a for blank holder are located at the upper part of a receiving jig 21 and a plate stock 20 is mounted on the upper face of the receiving jig 21. One part of the surface of the plate stock 20 located above a recessed groove 22 is pressed by the roller 14 with constraining the surface of the plate stock 20 located at both sides of the part A to be pressed by the rollers 15a, 15a for blank holder and extruded up to the specified depth. A pressurizing shaft 17 is then moved in the specified amt., the rollers 15a, 15a for blank holder are rotated with constraining the plate stock 20 and moved with extruding the plate stock 20 downwards. The extrusion part 26 extending in the moving direction of the roller 14 is thus formed on the plate stock 20. The depth of the extrusion part 26 is freely varied by varying the extrusion amt. and the length of the extrusion part 26 is freely varied by changing the moving distance of the roller 14.