PURPOSE: To always form a dynamic pressure generating groove with good accuracy by shaping an electric discharge machining electrode easily even if the electrode is worn.

CONSTITUTION: The electrodes 4 of an electrode collective body 3 are arranged in such a shape as the pattern of a dynamic pressure generating groove 2 to be formed at a rotating shaft 1 is developed in a plane shape. By generating discharging between the electrode 4 and the surface of the rotating shaft 1 while rotating and moving the rotating shaft 1 to form the dynamic pressure generating groove 2, the dynamic pressure generating groove 2 is formed at the surface of the rotating shaft 1. When the electrode 4 of the electrode collective body 3 has been worn by more than a prescribed amount by forming the dynamic pressure generating groove 2 at the surfaces of a plurality of rotating shafts 1, the surface of the electrode collective body 3 is shaped with wire electric discharge machining, a grinding wheel or the like. The electrodes 4 of the electrode collective body 3 are arranged on a plane, so it is possible to shape the surface of the electrode collective body 3 only by grinding it in a plane shape.