Patent ID: 8077402

Claim:
An imaging lens used for forming an image of an object on an image-taking surface of an image sensor element consisting of: in order from an object side to an image surface side, a diaphragm, a first lens that is a biconvex lens, and a second lens that is a lens having a negative power whose concave surface faces the object side, wherein conditions expressed by the following expressions (1), (2) and (5) are to be satisfied: −0.3 ≦r 1 /r 2 <−0.1 (1) 0.8 ≦f 1 /FL≦ 0.98 (2) 0.1 ≦d 1 /FL≦ 0.3 (5) where, r 1 : center radius curvature of the object side face of the first lens r 2 : center radius curvature of the image surface side face of the first lens f 1 : focal distance of the first lens FL: focal distance of the entire lens system d 1 : center thickness of the first lens.