A thrust dynamic pressure bearing with high inclination-resistant rigidity
against axis runout and additionally low bearing loss torque is
implemented. Herringbone grooves (131) having intermediate bends (132)
are provided on rotating-side bearing surface (11) provided on the
rotating-side bearing member. When rotating-side bearing surface (11)
rotates in direction A (clockwise), lubricating oil generates dynamic
pressure in an area centering on intermediate bend (132) along radially
outer part (133) and radially inner part (134) of herringbone groove
(131). As a result that groove width (G) of a dynamic pressure generating
groove and width (L) of a land adjacent to the dynamic pressure
generating groove holds G>L at an arbitrary radius (2) position, a
thrust dynamic pressure bearing with high inclination-resistant rigidity
and additionally low bearing loss torque is provided.