Abstract: An imaging lens includes first, second, third, and fourth lens elements arranged from an object side to an image side in the given order. The first lens element has a positive refractive power, and a convex object-side surface. The second lens element has a negative refractive power, and an image-side surface with a convex portion. The third lens element has an object-side surface with a concave portion. The fourth lens element has an object-side surface with a convex portion, and an image-side surface with a convex portion and a concave portion.