a motor having permanent magnets received therein includes a rotor having a plurality of circular sheet irons deposited in turn , a plurality pairs of magnet receiving slots formed through the deposited sheet irons at a predetermined angle toward the outer surface of the rotor , and permanent magnets of different polarities received into the magnet receiving slots , wherein a magnetic flux leakage preventive groove having a predetermined width and depth is formed at the outer surface of the rotor at the center between the pair of magnet receiving slots .