A driving mechanism is provided, including a base unit, a frame, a holder, a first driving assembly, a sensing magnet, and a magnetic field sensor. The base unit has a polygonal structure. The frame is connected to the base unit. The holder is connected to the frame for holding an optical element, wherein the optical element defines an optical axis. The first driving assembly is disposed on the base unit and the frame, close to a first side of the base unit for driving the holder and the frame to move relative to the base unit along a horizontal direction perpendicular to the optical axis. The sensing magnet is disposed on the holder and close to a second side of the base unit, opposite to the first side. The magnetic field sensor is disposed on the base unit for sensing the sensing magnet.