A motorized vacuum pump apparatus, may include an electric motor operating in response to an electric signal, a pumping unit connected with a motor shaft of the electric motor, and a sound absorbing unit enclosing the pumping unit and having an inlet for sucking external air, a damping chamber and an outlet, wherein the sound absorbing unit is directly combined with the electric motor, and wherein the external air is compressed and supplied by the pumping unit to the damping chamber and discharged through the outlet such that noise is reduced by damping compressed air in the damping chamber.