An imaging lens includes a first lens having positive refractive power; a second lens; a third lens; a fourth lens having negative refractive power; a fifth lens; and a sixth lens, arranged in this order from an object side to an image plane side with spaces in between each of the lenses. The first lens is formed in a meniscus shape to have an object side convex surface. The third lens is formed in a meniscus shape. The fourth lens has an object side concave surface. The fifth lens has two aspheric surfaces. The sixth lens has two aspheric surfaces and the image plane side convex surface. The fifth lens has a specific thickness, and the sixth lens has a specific thickness. The fourth lens has a specific Abbe's number. The fifth lens has a specific Abbe's number.