A zoom lens system, in order from an object side to an image side, comprising a first lens unit having negative optical power, a second lens unit having positive optical power, and at least one subsequent lens unit having optical power, wherein in zooming from a wide-angle limit to a telephoto limit, the lens units are moved along an optical axis such that an air space between at least any two lens units among the lens units should vary, so that variable magnification is achieved, wherein the first lens unit includes a lens element having a reflecting surface for bending a light beam incident from the object, and wherein the condition is satisfied: 0.20