An imaging lens includes a first lens; a second lens; a third lens; a fourth lens; a fifth lens having positive refractive power; a sixth lens; a seventh lens; an eighth lens; and a ninth lens, arranged in this order from an object side to an image plane side. The imaging lens has a total of nine lenses. The first lens has at least one aspheric surface. The ninth lens is formed in a shape so that a surface thereof on the image plane side has an aspherical shape. The ninth lens has a specific focal length.