A lens module includes a lens barrel, and a lens group received by the lens barrel. The lens barrel includes an first supporter, a second supporter extending vertically from the first supporter, and a receiving space formed by those supporters, the first supporter having a light aperture, the second supporter having an inner surface facing the receiving space. The lens group includes a first lens abutting against the inner surface of the second supporter, a second lens stacked on the first lens and abutting against the inner surface of the second supporter, a third lens stacked on the second lens and abutting against the inner surface of the second supporter, and a fourth lens stacked on the third lens and abutting against the inner surface of the second supporter, for ensuring the concentricity among the lenses and keeping the lens group coaxial with the lens barrel.