A hydrodynamic bearing device capable of inhibiting leakage of a working
fluid to an outside of a bearing and preventing reduction in radial
bearing rigidity, and capable of keeping a gap between a thrust bearing
and a radial bearing favorable and rotating stably. The hydrodynamic
bearing device includes a shaft relatively rotatably inserted into a
bearing hole of a sleeve, a radial bearing surface having dynamic
pressure generating grooves formed on at least one of an outer peripheral
surface of the shaft and an inner peripheral surface of the sleeve, and a
gap filled with a working fluid between the shaft and the sleeve. The
shaft is made of high manganese chrome steel or stainless steel, and the
sleeve is entirely made of sintered metal of metal particles including at
least 60% by weight of iron or copper. Resin, metal or water glass is
impregnated in pores on a surface of the sintered metal and cured.
Thereby, leakage of the working fluid to the outside of the bearing from
the sleeve can be inhibited, and reduction in the pressure inside the
bearing can be prevented.