Disclosed herein is a hydrodynamic bearing which has improved ability to efficiently seal fluid (lubricant), which generates dynamic pressure. The hydrodynamic bearing provides a fluid storage space that couples a fluid reservoir with a hydrodynamic space, in addition to a fluid reservoir defined by a spacer and a cover. The fluid storage space has a cross-section that gradually tapers in a fluidsupply direction, thus serving as an additional fluid reservoir for sealing fluid and supplying the fluid to the hydrodynamic space, when necessary. Further, unlike the prior art, where a fluid surfaceis controlled in a relatively narrow fluid reservoir, the fluid surface can be controlled in a relatively wide fluid storage space, and air bubbles generated in the hydrodynamic space can be easilydi scharged to the outside, thus affording convenience when the hydrodynamic bearing is used.