An imaging lens includes a first lens having positive refractive power; a second lens; a third lens; a fourth lens; a fifth lens; a sixth lens; and a seventh lens, arranged in this order from an object side to an image plane side with a space between each of the lenses. The third lens is formed in a shape so that a surface thereof on the image plane side has a positive curvature radius. The sixth lens is formed in a shape so that a surface thereof on the image plane side has a positive curvature radius. The seventh lens has a specific Abbe's number. The sixth lens has a specific focal length. The seventh lens has a specific focal length.