An optical element driving mechanism is provided. The optical element driving mechanism includes a fixed portion, a movable portion, a driving assembly, and a circuit unit. The movable portion is movably connected to the fixed portion, and holds an optical element. The driving assembly drives the movable portion to move relative to the fixed portion. The circuit unit includes a base, a plate-connecting portion, and a layer-connecting portion. The plate-connecting portion is partially embedded in the base. The layer-connecting portion is disposed on the base. The driving assembly is electrically connected to the layer-connecting portion. The thickness of the plate-connecting portion is different from the thickness of the layer-connecting portion.