To provide a forming die device for welding projections in a punch press, and a method for working welding projections capable of forming welding projections without any hole in point-contact with a counter workpiece in a resistance welding system, simple in configuration, easy in manufacture, and capable of ensuring the die rigidity when forming a plurality of welding projections for the multipoint simultaneous welding used in the resistance welding system are formed in a narrow area on the workpiece at a short spacing.

The forming die device for welding projections comprises a punch die P and a die D, a plurality of extrusion-forming parts 1, 2 to form a welding projection T with a pointed tip are provided on the punch die P or the die D, and the corresponding die D or punch die P is formed flat.