An image pickup lens system includes a lens 1 of a meniscus shape having a first face as a .[.convex.]. .Iadd.concave .Iaddend.face, and a diaphragm 2 disposed on an object side of the lens 1. The lens 1 meets the following conditions: Y'/fl equal to or larger than 0.6; Dt/Dc is equal to or smaller than 0.9 and equal to or larger than 0.5; and Ap.sub.2/Am.sub.2 is equal to or larger than 0.9. Thus, even when an image pickup element is of a reduced size, a desired optical performance can be maintained, and it is possible to produce a lens easily with a back focal length ensured.