Abstract: A motion transforming mechanism comprises a plate assembly and a toothed rail. The plate assembly is constituted by at least three rotation plates having a common rotation axis and each having a plurality of teeth, the rotation plates being respectively formed with cranked through bores. The toothed rail is formed with a plurality of teeth held in mesh with the teeth of rotation plates. The motion transforming mechanism further comprises a drive motor assembly constituted by a rotor unit rotatably received in the cranked through bores and a stator unit accommodated in the rotor unit. The rotation plates are rotated with respect to their common rotation axis by the rotation of the rotor unit with respect to stator unit. The motion transforming mechanism thus constructed requires no external electric motor and accordingly is able to be more easily assembled with various systems.