A motor structure with built-in lens includes a lens mount (10) defining an inner space therein, a hollow stator (32) fixedly received in the inner space, a rotor (34) rotatably received in the stator with an internal thread (344) defined in an inner surface thereof, and a lens unit (50) received in the rotor. The lens unit defines an external thread (544) on an outer surface thereof threadedly engaging with the internal thread of the rotor. A protrusion (328) is formed on an inner surface of the stator for supporting an outer surface of the rotor thus obtaining stable rotation of the rotor.