Imaging lens

1. An imaging lens comprising:

a first lens having positive refractive power;

a second lens having positive 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 third lens is a meniscus lens with a convex surface directed to an object side in an axial region,

said eighth lens is a meniscus lens in the axial region,

said ninth lens is a meniscus lens directing a convex surface thereof to the object side in the axial region and formed in a shape so that a surface thereof on the image plane side has an aspherical shape having an inflection point, and when the whole lens system has a focal length f, a distance on an optical axis between the eighth lens and the ninth lens is D89 and a paraxial curvature radius of an image plane-side surface of the ninth lens is R9r, so that the following conditional expressions are satisfied:

0.01< D 89/ f< 0.20

0.2< R 9 r/f< 1.0.

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

0.3< f 2/ f< 1.2.

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

−3.5< f 3/ f<− 1.0.

4. The imaging lens according to claim 1 , wherein said third lens has a focal length f3 and said fourth lens has a focal length f4 so that the following conditional expression is satisfied:

4< f 4/ f 3<20.

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

−4.0< f 9/ f<− 0.5.