A fluid dynamic pressure bearing having a tapered seal part provided between a sleeve and a housing, from which lubricating liquid is injected and functions as a buffer of the lubricating liquid. The support platform is movably attached to the slide for movement in a second direction generally orthogonal to the first direction. The retaining member includes multiple protruding members positioned substantially perpendicular to the support member to form multiple tapered slots which can have openings of varying widths.