An exemplary camera module includes a lens holder and a lens barrel. The lens holder includes a cylindrical receiving cavity defined therein and an inner smooth surface in the cylindrical receiving cavity. The lens barrel is received in the cylindrical receiving cavity. The lens barrel includes a hollow cylinder and a plurality of spaced protrusions arranged on the outer cylindrical surface of the hollow cylinder. The outer cylindrical surface is spaced from the inner smooth surface. The protrusions abut against the inner smooth surface.