A lens module includes a lens barrel, a first lens, a second lens, a third lens, and two spacers. The lens barrel includes an object-side end and an image-side end. The first, second, and third lenses are received in the lens barrel and arranged in that order from the object-side to the image-side. One of the two spacers is positioned between the first lens and the second lens, and the other of the two spacers is positioned between the second lens and the third lens. Each of the spacers is chamfered to prevent the ingress of unwanted light.