Hydrodynamic bearing

A hydrodynamic bearing includes first and second thrust plates (2,3) held against respective axially opposite ends of a cylindrical radial bearing member (1), and a cylindrical radial sleeve (4) provided concentrically with the cylindrical radial bearing. The outer circumferential surface of the cylindrical radial bearing member (1) and the inner circumferential surface of the cylindrical radial sleeve (4) serve as sliding surfaces jointly making up a radial hydrodynamic bearing assembly, and the confronting surfaces (2a,3a) of the first and second thrust plates (2,3) and the end surfaces of the cylindrical radial sleeve (4) serve as sliding surfaces jointly making up a thrust hydrodynamic bearing assembly. At least one of the sliding surfaces of the thrust hydrodynamic bearing assembly has grooves (c) formed therein for generating a hydrodynamic pressure. At least one of the sliding surfaces of the radial hydrodynamic bearing assembly is coated with a uniform hydrogenated amorphous carbon film (b). At least one of the sliding surfaces of the thrust hydrodynamic bearing assembly is coated with a uniform hydrogenated amorphous carbon film (b).