To widen a viewing angle while securing required back focus though compact and inexpensive 2-lens constitution by adopting a lens on an object side of a retro-focus type whose surface on the object side is a convex surface and satisfying prescribed two conditional expressions.

This lens is constituted of the two lenses L1 and L2, a first lens L1 is a negative meniscus lens turning the convex surface to the object side and a second lens L2 is a biconvex lens provided with mutually almost similar curvatures. By adopting the first lens L1 of the retro-focus type whose surface on the object side froms the convex surface, distortion is excellently corrected and the viewing angle is widened. Also, by making body surfaces of the respective first lens L1 and second lens L2 aspherical, various aberrations are improved.