To provide an inexpensive and compact imaging lens for a solid-state image pickup device which has good optical performance.

The imaging lens is composed of an aperture diaphragm, a first positive lens, a second negative lens and a third negative lens in this order from an object side. The surface on the image side of the third lens is made into an aspherical shape. On the aspherical surface, the part near the optical axis has a concave surface on the image side, and the peripheral part has a convex surface on the image side.