An imaging lens includes a first lens having negative refractive power; a second lens having positive refractive power; a third lens having positive refractive power; a fourth lens having negative refractive power; a fifth lens; and a sixth lens having negative refractive power, arranged in this order from an object side to an image plane side. The fourth lens is disposed to face the fifth lens. The fourth lens is formed in a shape so that a surface thereof on the image plane side is concave at a peripheral portion thereof. The fifth lens is formed in a shape so that a surface thereof on the object side is concave at a peripheral portion thereof.