A zoom lens system includes a first lens group which has a negative refractive power, a second lens group which has a positive refractive power, and a third lens group which has a positive refractive power in this order from the object side and changes the distances among these lens groups to vary the power from the wide-angle end to the telephoto end. The second lens group has a three-element cemented lens including a positive lens c1, a negative lens c2, and a positive lens c3.