A zoom lens system comprising at least three lens groups including a positive first lens group, a positive second lens group having at least one negative lens element, and a third lens group having a negative focal length, wherein upon zooming from the shortest focal length toward the longest focal length, all the lens groups are moved toward the object side, and the distance between the first and second lens groups increases and the distance between the second and third lens groups decreases, and wherein the system satisfies the conditions (1) -0.3 0), f.sub.2G designates the focal length of the second lens group (f.sub.2G >0), f.sub.3G designates the focal length of the third lens group (f.sub.3G