An imaging lens includes first, second, third, fourth, and fifth lens elements arranged from an object side to an image side in the given order. The first, second, and third lens elements have positive, negative, and negative refractive powers, respectively. The third lens element has an image-side surface having a convex portion in a vicinity of a periphery of the third lens element. The fourth lens element has a concave object-side surface. The fifth lens element has an object-side surface that has a convex portion in a vicinity of an optical axis of the imaging lens, and an image-side surface that has a concave portion in a vicinity of the optical axis and a convex portion in a vicinity of a periphery of the fifth lens element.