The imaging lens system includes a negative first lens disposed on a most object side, having a concave surface directed toward the object side and having a meniscus shape, a cemented lens LC disposed on a most image side and having a convex surface on its most object side, and an aperture diaphragm disposed just in front of the object side of the cemented lens. The system satisfies the following conditional expressions: 0.05 15 where R1 and R2 denote radius of curvatures of object side and image side surfaces of the first lens, respectively, and vd1 and vd2 denote Abbe numbers of lenses, which are located on the most object side and on the most image side among lenses constituting the cemented lens, at the d-line, respectively.