A conical hydrodynamic bearing device comprises a shaft bush having a conical inclined dynamic pressure surface around an outer circumference thereof being relatively-rotatably inserted in a bearing sleeve having a conical inclined dynamic pressure surface around an inner circumference thereof, so that a conical inclined bearing space is created in a gap between the inclined dynamic pressure surfaces of the bearing sleeve and shaft bush. A lubricant fluid is filled inside the inclined bearing space. A proper dynamic pressure generating means is formed on at least one of the inclined dynamic pressure surfaces of the shaft bush and bearing sleeve. The lubricant fluid is pressurized by the dynamic pressure generating means to generate dynamic pressure, by which the shaft bush and the bearing sleeve are relatively elevated in the radial and thrust directions so that their rotations are supported in a non-contact manner. An open angle .theta.1 created by a pair of generatrixes between which a plane including the center axis of the shaft bush intersects with the inclined dynamic pressure surface of the shaft bush which is set to be larger than an open angle .theta.2 created by a pair of generatrixes between which a plane including said center axis of the bearing sleeve intersects with the inclined dynamic pressure surface of the bearing sleeve (.theta.1>.theta.2).