An imaging lens system, in order from the object side to the image side thereof, includes a first lens with positive refractive power, and a second lens with positive refractive power. The imaging lens system satisfies the following formulas: 1.2≦TTL/f≦2.0, where image sensing element TTL is the distance along an optical axis thereof from the object-side lens surface of the first lens to an imaging plane, f is the focal length of whole the image lens system.