A zoom lens system includes, arranged sequentially from an object side, a first lens group including at least one reflective optical member changing the optical path of an incident light ray, and having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; and a fourth lens group having positive refractive power, and during a magnification change from a wide-angle position to a telephoto position, the first lens group and the third lens group are not moved, the second lens group is moved from the object side towards an image side, and the fourth lens group is linearly moved from the image side towards the object side.