A zoom lens system includes a positive first lens group, a negative second lens group, a positive third lens group, a negative fourth lens group, and a positive fifth lens group having a plurality of lens elements. During zooming from the short to long focal length extremities, at least the first, third and fifth lens groups move in an optical axis direction. A surface closest to the image side of the zoom lens system is a concave surface facing the image side. The following condition (1) is satisfied: 0.52