A high-accuracy, long-life hydrodynamic bearing that does not cause oil
film breakage in bearing clearances and a disc rotation apparatus using
the bearing is disclosed. Oil film breakage is avoided as negative
pressure is prevented from generating between the shaft and sleeve of the
hydrodynamic bearing. Herringbone shaped dynamic pressure generating
grooves, located on the thrust bearing section and the radial bearing
section of the hydrodynamic bearing, are oil filled and have optimum
shapes. The optimum shapes prevent the generation negative pressure and
thus prevents the coagulation of air bubbles that can cause oil film
breakage. The disc rotation apparatus, that holds a
reproduction/recording disc, is concentrically secured to the
hydrodynamic bearing and rotated. The disc is put into contact with
magnetic or optical heads while rotating in the disc rotation apparatus.
Both the hydrodynamic bearing and the disc rotation apparatus experience
high reliability.