PURPOSE: To work dynamic pressure generating grooves having an ideal rectangular shape with exact dimensional accuracy by irradiating the bearing surfaces of bearings constituting dynamic pressure bearings by facing each other with beams to harden the surfaces to prescribed groove patterns, then etching the surfaces.

CONSTITUTION: The bearing surfaces 1 constituting the dynamic pressure bearing 25 of a shaft 20 by facing each other are irradiated with beams according to the dynamic pressure generating groove patterns previously provided on at least one of the bearing surfaces 1 to form the patterns of the wave shapes consisting of hardened parts 12 and non-hardened parts 13. After the surface roughened parts of this bearing surface 1 are removed, the surfaces are immersed for a prescribed period of time into an etching liquid to form the dynamic pressure generating grooves 10, 11 in the non-hardened parts 13. The dynamic pressure generating grooves 10, 11 having the sectional shape approximate to the rectangular shape and the exact dimensional accuracy with lessened shape collapse are easily obtd. in this way.