A zoom lens optical system having a third lens unit including a first correction lens unit of negative (-) power and a second correcting lens unit arranged behind the first correcting lens unit in an optical path and having positive (+) power. The system can minimize aberration variation upon hand-shaking correction and obtain high resolution upon OIS application since the third lens unit for correcting the hand-shaking is formed with a lens group of plural lenses having negative (-) power and positive (+) power. Further, the system can enhance a response speed since the minimization of aberration variation upon the hand-shaking correction can reduce driving load when lenses move due to short movement distance of the third lens unit.