The imaging lens system includes, from the object side, a diaphragm, a first lens as a positive meniscus lens whose convex surface faces the object side, and a second lens as a positive lens whose convex surface faces the image surface side, wherein the following expressions are to be satisfied 1.25.gtoreq.L/fl.gtoreq.0.8, 1.gtoreq.f.sub.1/f.sub.2>0.55, 1.8.gtoreq.f.sub.1/fl.gtoreq.1, 4.gtoreq.f.sub.2/fl.gtoreq.1.5, 1.gtoreq.d.sub.2/d.sub.1.gtoreq.0.5, 0.27.gtoreq.d.sub.1/fl.gtoreq.0.1, 0.27.gtoreq.d.sub.3/fl.gtoreq.0.1 (where, L: entire length of the lens system, fl: focal distance of entire lens system, f.sub.1: focal distance of the first lens, f.sub.2: focal distance of the second lens, d.sub.1: center thickness of the first lens, d.sub.2: distance between the first lens and second lens on the optical axis, d.sub.3: center thickness of the second lens).