As axis direction dimensions become smaller in HDD spindle motors as a result of thinner and more compact designs, there is a demand for hydrodynamic bearings with a long lifespan. As a means of solving this problem, a lubricant reservoir section is formed between a sleeve side surface and a cover side surface with a depth varying in a circumferential direction, lubricant is circulated in a bearing gap section, a sleeve end face gap section larger than a bearing gap between a sleeve end face and the cover, and a connecting channel, and the lubricant reservoir section and the sleeve end face gap section are connected via an introducing gap section having a bubble separation function.