An imaging lens includes a first lens group; a second lens group; and a third lens group. The first lens group includes a first lens, a second lens having negative refractive power, and a third lens. The second lens group includes a fourth lens and a fifth lens. The third lens group includes a sixth lens and a seventh lens. The first to seventh lenses are arranged on an optical axis with a space in between respectively. The first lens is formed in a meniscus shape. The third lens has a surface on an image plane side having a positive curvature radius. The fourth lens has a surface on the image plane side having a negative curvature radius. The sixth lens is formed in a meniscus shape. The seventh lens has a surface on the image plane side having a positive curvature radius and formed in an aspheric shape.