An imaging lens includes a first lens, a second lens, a third lens, an aperture stop, and a fourth lens, sequentially arranged from the object-side of the imaging lens. The first lens has negative power, and an object-side surface is convex and an image-side surface is concave. Both surfaces of the second lens are aspheric, and in the vicinity of the optical axis, the second lens has negative power, and the object-side surface is convex and the image-side surface is concave. Both surfaces of the third lens are aspheric, and in the vicinity of the optical axis, the third lens has positive power, and the object-side surface is convex, and the image-side surface is concave. Both surfaces of the fourth lens are aspheric, and in the vicinity of the optical axis, the fourth lens has positive power, and the object-side surface is concave, and the image-side surface is convex.