A motor having a fluid dynamic bearing generating a fluid dynamic pressure by forming an oil gap between a rotor and a stator such that oil is accommodated in the oil gap, and a first and second air dynamic bearing generating an air dynamic pressure by forming an air gap between the rotor and the stator such that air is introduced into the air gap. The fluid dynamic bearing generates a fluid dynamic pressure by forming an oil gap between an axial hole of a sleeve and a shaft such that oil is accommodated in the oil gap, and the first and second air dynamic bearings generate an air dynamic pressure by forming an air gap between an inner circumferential surface of a hub and an outer circumferential surface of the sleeve and between the inner circumferential surface of the hub and an upper plane surface of the sleeve, respectively.

Provided is a motor, which can minimize friction caused during initial operation and smoothly discharge static electricity generated during operation by employing both an air dynamic bearing and a fluid dynamic bearing using oil of predetermined viscosity. Bearing means employed in the motor includes a fluid dynamic bearing generating a fluid dynamic pressure by forming an oil gap between a rotor and a stator such that oil is accommodated in the oil gap, and an air dynamic bearing generating an air dynamic pressure by forming an air gap between the rotor and the stator such that air is introduced into the air gap. Specifically, the fluid dynamic bearing generates a fluid dynamic pressure by forming an oil gap between an axial hole of a sleeve and a shaft such that oil is accommodated in the oil gap, and the air dynamic bearing generates an air dynamic pressure by forming an air gap between an inner circumferential surface of a hub and an outer circumferential surface of the sleeve. Since the motor employs both the fluid dynamic bearing and the air dynamic bearing, dry friction between the rotor and the stator is prevented during operation, thereby improving operating characteristics. Also, since the motor secures a path through which static electricity generated by air friction in a clearance of the air dynamic bearing is discharged, the motor can satisfy requirements of hard disk drives (HDDs) employing the motor.

Provided is a fluid dynamic bearing motor in which a rotor is rotatably supported by forming an oil gap between the rotor and a stator to form a fluid dynamic pressure bearing and a plurality of oil grooves are formed in a surface of the rotor or stator forming the oil gap and facing each other. The oil grooves include a first oil groove inclined at a first angle with respect to a circumferential direction, and a second oil groove extending from an end portion of the first oil groove and inclined at a second angle with respect to the circumferential direction. The first angle is formed relatively greater than the second angle.