There are provided an imaging lens, which is capable of promoting high definition and miniaturization of a small-size image pickup apparatus, and the small-size image pickup apparatus using the same. A aperture diaphragm S is arranged between a first lens L1 and a second lens L2 so that the first lens L1 is configured to be displaced into the orthogonal direction to the optical axis. Even when an error sensitivity of a lens is large, a stable high resolution can be secured by performing a lens alignment by displacing the first lens L1 into the orthogonal direction to the optical axis at the time of assembling, and thereby a high definition image can be obtained.