1. An imaging lens comprising, in order from the object side and without any intervening lens components, the following: a first lens component of positive refractive power and a meniscus shape with its convex lens surface on the object side; a second lens component of positive refractive power and a meniscus shape with its convex lens surface on the image side; and a third lens component of negative refractive power and having a concave lens surface on the image side; wherein both lens surfaces of said third lens component are aspheric; and the negative refractive power of said third lens component gradually decreases from the center of said third lens component toward the periphery of said third lens component and the peripheral region of said third lens component has positive refractive power.