A zoom lens system of the present invention has a plurality of lens units each composed of at least one lens element and, in order from the object side to the image side, comprises: a first lens unit having negative optical power and composed of two lens elements; a second lens unit having positive optical power; and a third lens unit having positive optical power, wherein in zooming, the lens units are moved such that an interval between the first lens unit and the second lens unit should decrease and that an interval between the second lens unit and the third lens unit should increase, so that magnification change is achieved, and wherein the condition is satisfied: 1.5 4.0, ωW>35, Ir: a maximum image height (Ir=fT×tan (ωT)), LT: an overall length at a telephoto limit (a distance from the most object side of the first lens unit to the image surface), fT, fW: focal lengths of the entire system at a telephoto limit, a wide-angle limit, ωW, ωT: half values of maximum view angles at a wide-angle limit, a telephoto limit.