A motor comprises a base plate with an axle seat to which a stator bobbin is mounted. The stator bobbin comprises an axle hole for rotatably receiving a shaft of a rotor. The rotor comprises a permanent ring magnet. A balance ring is mounted to the base plate and comprises an upright annular wall and an annular bottom wall. The upright annular wall of the balance ring and a lower section of the permanent ring magnet attract each other while the annular bottom wall of the balance ring and a lower end face of the permanent ring magnet attract each other.