A lens module includes a lens supporter, and a lens group received by the lens supporter. The lens supporter includes an aperture plate, a main body extending downwardly from the aperture plate and a receiving space formed by the aperture plate and the main body, the aperture plate having a light aperture, the main body having an internal surface facing the receiving space. The lens group includes a first lens abutting against the aperture plate for forming a first alignment accuracy, a second lens stacked on the first lens and keeping a distance from the internal surface of the main body, a third lens stacked on the second lens and keeping a distance from the internal surface of the main body, and a fourth lens stacked on the third lens and abutting against the internal surface of the main body.