A hydrodynamic bearing assembly according to an aspect of the invention may include: a sleeve against which a shaft is supported so that an upper end of the shaft, being compressed and inserted into a hub base of a rotor case, protrudes upwardly in an axial direction; a first oil sealing unit having a first oil interface provided between the hub base and a counterpart component arranged downwardly in the axial direction; and a second oil sealing unit communicating with the first oil sealing unit through a communication channel and being tapered to form a second oil interface inside or outside the sleeve, wherein oil in the first oil sealing unit moves toward the second oil sealing unit along an inner diameter direction by a rotation of the rotor case.