PURPOSE: To reduce the manufacturing processes in an elbow for piping of air and the like by forming a shrank diameter cylindrical part in each of plural curved cylindrical bodies in the end part of the axial direction and connecting plural curved cylindrical bodies together so that the shrank diameter cylindrical part is formed in each of both end parts of a connection body.

CONSTITUTION: A bottomed curved cylindrical body 7 made of a metal plate is extruded and formed by a press male die 8 and a press female die 9, both of which move circularly setting a rotational center 10 as the center. The bottom part 6 of the bottomed curved cylindrical body 7 is pressed further by a point shrank diameter cylindrical body forming part 11 of the press male die 8, so that a shrank diameter cylindrical part. is formed between the point shrank diameter cylindrical body forming part 11 and the a shrank diameter cylindrical body forming part 12 in the end of the female die 9. A connection body is formed by connecting the curved cylindrical bodies, in each of which a shrank diameter cylindrical part is formed in its end part in this way, together so that the shrank diameter cylindrical parts are located in both ends.