The embodiments of the present disclosure provide a shaft structure of a motor, comprising a housing, a stator disposed inside the housing, and a rotor rotatably disposed inside the stator. The stator may comprise a stator core and a coil wound around the stator core, and the rotor may comprise a rotor core and a rotational shaft coupled to the rotor core. The rotational shaft may comprise a plurality of adjusting portions formed on an outer circumferential surface of the rotational shaft to align a center of gravity of the rotor with a center of the rotational shaft.