A zoom optical system includes three lens groups, arranged as follows from the object side: a first lens group having positive refractive power, a second lens group having negative refractive power, and a third lens group having positive refractive power. The first lens group includes, arranged as follows along the optical axis, a lens element having negative refractive power, a prism for bending the optical axis, and a lens element having positive refractive power. The second and third lens groups are movable along the optical axis for zooming with only the third lens group reversing its direction of movement along the optical axis during zooming from the wide-angle end to the telephoto end. The third lens group includes a stop, a cemented lens component, and at least one aspheric surface that may be made of plastic. The first lens group also includes at least one aspheric surface.