A compact imaging lens system includes three lenses. The first lens is a positive meniscus lens having a convex side facing toward the image side, which has a big focusing power and is provided to capture image and for balance of aberration. The first lens serves to make the lens system a low sensitivity lens system. The second lens is a negative lens and is provided mainly for correcting chromatic aberration and off-axis aberration. An aperture is set between the first and second lenses, and this is of benefit to balance of aberration. The third lens is a negative lens and is provided for correcting off axis aberration. All the lenses can be made of plastics. This facilitates cost reduction, weight reduction, while still maintains a high resolution.