To implement forming of thrust dynamic pressure grooves on a flange together with fastening of a shaft highly precisely, reduce costs and improve mass productivity.

The thrust dynamic pressure grooves Mu, Md are formed on front and back faces of a flange material by pressing the flange material, and at the same time, the shaft S fitted to a shaft center hole Fc of the flange material is fastened. In order to implement these, in a basic press device A1, by pressing the flange material with an upper die 1 and a lower die 2 that have molding projecting portions 3u, 3d of the dynamic pressure grooves in a closed state where expansion of the outer diameter portion of the flange material is regulated by an outer diameter restraining plate 5, the thrust dynamic pressure grooves Mu, Md are formed, and the shaft S is fastened into the shaft center hole Fc by reducing the inner diameter of the flange F.

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