A fluid dynamic bearing is provided. A structure in which a shaft member and an annular member fitted about the shaft member are rotatably supported by a bearing member and an annular member on the bearing member has a fifth gap for storing a lubricating fluid and supplying it to a second gap below the annular member on the shaft member and a third gap around its outer periphery through a fourth gap. The fourth and fifth gaps are tapered to produce a capillary drawing force toward the third and second gaps, so that the lubricating fluid may be supplied effectively from the fifth gap to the second and third gaps. This makes it possible to suppress any sudden formation of a reduced pressure upon exposure to impact or vibration to prevent the leakage of any lubricating fluid caused by the generation of bubbles, while making up for the loss of any lubricating fluid by vaporization.