PURPOSE: To excute easily and exactly cold forging of parts such as a small screw for clock, etc., by forming the first punch of a cold forging machine as an air passing structure, and making air collecting in the inside flow out.

CONSTITUTION: In case of cold forging of a small screw for a clock, a special pin, etc., the first punch is formed as a structure consisting of an air passing hole 14 and an air passing groove 15 provided on a cavity 6 between a sintered hard frame 1 and a sleeve 3. By this first punch structure, air having a damper state generated in the cavity 6 between the sintered hard frame 1 and the sleeve 3 flows out of the system. By this tool structure, a small-sized blank material can be cold-forged exactly.