Zoom lens system, imaging device and shooting apparatus

The present invention provides a zoom lens system comprising a first lens unit having negative power, a second lens unit having positive power and a third lens unit having positive power, wherein in zooming from a wide-angle limit to a telephoto limit, the lens units move respectively along an optical axis in such a manner that an interval between the first lens unit and the second lens unit decreases while an interval between the second lens unit and the third lens unit changes so that variable magnification is achieved, the first lens unit comprises one object side negative lens element and one image side positive lens element with a convex surface facing the object side, which have an aspheric surface, and the conditions: n12>188 and v12