Imaging lens

1. An imaging lens comprising:

a first lens having positive refractive power;

a second lens having negative refractive power;

a third lens having negative refractive power;

a fourth lens having negative refractive power;

a fifth lens; a sixth lens;

a seventh lens;

an eighth lens; and

a ninth lens having negative refractive power,

arranged in this order from an object side to an image plane side,

wherein said second lens has a meniscus shape with a convex surface on the object side near an optical axis,

said ninth lens is formed in a shape so that a surface thereof on the image plane side has an aspherical shape having an inflection point, and

said ninth lens is formed in a shape so that a surface thereof on the image plane side has a said ninth lens is formed in a shape so that a surface thereof on the image plane side has a paraxial curvature radius R9r so that the following conditional expression is satisfied:

0.2< R 9 r/f< 0.8,

where f is a focal length of a whole lens system.

2. The imaging lens according to claim 1 , wherein said first lens has a focal length f1 and said second lens has a focal length f2 so that the following conditional expression is satisfied:

−6< f 2/ f 1<−1.

3. The imaging lens according to claim 1 , wherein said second lens has a focal length f2 and said third lens has a focal length f3 so that the following conditional expression is satisfied:

4< f 3/ f 2<12.

4. The imaging lens according to claim 1 , wherein said ninth lens has a focal length f9 so that the following conditional expression is satisfied:

−3.5< f 9/ f<− 0.2,

where f is a focal length of a whole lens system.