PURPOSE: To make the degree of freedom of design large, improve the performance, and lighten the load on a lens barrel by composing the lens of three elements in two groups and using gradient index type lenses for two of the three lenses.

CONSTITUTION: The lens consists of contact glass 10, the 1st-3rd lenses 11-13, and the cover glass 14 of a solid-state image pickup-element. Namely, the 1st-3rd lenses 11-13 are arranged in order from the object side to the image side and the three-group, twoelement constitution wherein the 2nd lens 12 is cemented to the 1st lens 11 or 3rd lens 13 is obtained; and the 1st lens 11 and 3rd lens 13 are the gradient index type lenses. Further, a meniscus lens which has a convex surface on its object side is used as the 1st lens 11, a convexo-plane lens which has a convex surface on its object side is used as the 2nd lens 12, and a plano-concave lens which has a concave surface on its image side is used as the 3rd lens 13; and the 2nd lens 12 and 3rd lens 13 are cemented and gradient index distribution types which vary in refractive index in the optical axis directions may be used as the 1st lens 11 and 3rd lens 13.