PURPOSE: To execute smooth curved bulging by fitting a rubber-like elastic body into a cylindrical rising flange, then, pressing the top part of the burred cylindrical rising flange with a punch and at the same time compressing a rubber-like elastic body with a punch on the die side.

CONSTITUTION: A cylindrical protrusion part A1 is formed at a part of a strip sheet and a pierce hole A2 is made at the cylindrical protrusion part A1, burred and formed into a cylindrical rising flange A3. When a cylindrical flange is bulged outward at the middle part, the cylindrical rising flange A3 is supported from the horizontal direction by a die which forms a flange holding surface of the same shape as the surface of a part or all of the cylindrical bulged flange on the inside and the rubber-like elastic body is fitted into the cylindrical rising flange. Then the rubber-like elastic body is compressed by a punch on the die side at the same time as the top part of the cylindrical rise flange A3 is pressed to form the cylindrical bulged flange A. In this manner, it is possible to obtain the smoothly curved cylindrical bulged flange A.