A variable focal length lens system realizing compactness and high zoom ratio is provided. The lens system includes four lens groups that are, in order from an object, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having positive refractive power. When the state of lens group positions varies from a wide-angle end state to a telephoto end state, at least the first lens group is moved to the object such that a distance between the first and the second lens groups increases, a distance between the second and the third lens groups decreases, and a distance between the third and the fourth lens groups varies. An aperture stop is arranged in the vicinity of the third lens group. Given conditional expressions are satisfied.