A lens module includes a plurality of lenses, an annular body and a reflective element. The reflective element, the lenses and the annular are sequentially arranged along an optical axis from an object side to an image side. The lenses include a first lens that is disposed closest to the object side, and a second lens that is disposed closest to the image side. The reflective element is disposed between the object side and the first lens. The annular body is disposed between the object side and the first lens, between the lenses, or between the second lens and the image side. The lens module satisfies 0.5 mm<EPA/PL<5.5 mm where EPA is an area of an entrance pupil of the lens module, and PL is a length of the reflective element.