The generation of bubbles can be suppressed by enabling a stable supply of working fluid to a dynamic pressure generating groove, and oscillation at the time of rotation and leakage of working fluid can be prevented effectively by efficiently releasing any bubbles generated. There is provided a fluid dynamic pressure bearing 1 provided with an annular dynamic pressure generating face 17 made by forming a dynamic pressure generating groove, which draws a working fluid 14 toward a midway position in the radial direction from the inside and outside of a thrust bearing plate 13 in the radial direction, when a shaft 10 and a housing 11 are rotated relative to each other about the axis, on thickness direction end faces 13a, 13b of the thrust bearing plate 13, or on an inner surface of the housing 11, and an inner groove section 16, which is located on an inner peripheral side thereof and that is depressed more than the dynamic pressure generating face 17 in the thickness direction, on the end faces 13a, 13b. Moreover there is provided a through hole 19 which passes through the thrust bearing plate 13 in the thickness direction so as to open to the dynamic pressure generating face 17, and there is provided a communicating cavity 20 which connects the opening portion of the through hole 19 and the inner groove section 16.