An imaging lens system includes a first lens 2 which is a meniscus lens with its convex face turned toward the object side and having a positive power, a diaphragm 3, and a second lens 4 which is a meniscus lens with its concave face turned toward the object side. The first lens 2, the diaphragm 3 and the second lens 4 are disposed sequentially in the named order from the side of the object toward an image surface. In the imaging lens system, the following conditional expressions are satisfied: 1.25flL0.8fl; 1.26flf₁0.85fl; 0.8d₁d₂0.35d₁; L6.25 mm; d₁0.225fl; and d₃0.225fl, wherein L is a distance of the entire length of the lens system; fl is a focal length of the entire lens system; f₁ is a focal length of the first lens; d₁ is a thickness of the center of the first lens; d₂ is a distance between the first and second lenses; and d₃ is a thickness of the center of the second lens.