PURPOSE: To form the spline groove closing both ends with less man-hour by forming one end of a cylindrical body in a spreading tapered flange, forming the plural spline grooves with its end part being closed in the inner face axial direction and deforming it in a cylindrical shape by a die and punch.

CONSTITUTION: The cylindrical blank having the inner and outer diameters in about the same dimension as those of a valve sleeve completed product is inputted between the die of a preforming die and a punch to obtain a primary intermediate body that the upper end part of a cylindrical body becomes of the tapered flange part spreading to the external part. Then, the intermediate body is inputted between a die 24 and punch 25 and a secondary intermediate body 27 forming plural spline grooves 20a' closing its tips is formed on the inner face of the cylindrical part by strongly pressing by a punch 26 to punch the bottom part in a circular shape. Then, the secondary intermediate body 27 is inputted in a drawing die 28 and by passing it through the die 28 by strongly pressing by the punch 30 having a mandrel the completed product 31 forming the spline groove 20a" whose both ends are closed on the inner face of the cylindrical body is obtd.