A variable focal length lens system comprises, from the object side, a positive first lens group, a positive second lens group and a negative third lens group. The lens groups are moved toward the object side such that, when changing from wide angle to telephoto, distance between the first lens group and the second lens group is increased and distance between the second lens group and the third lens group is decreased. An aperture stop disposed in the vicinity of the second lens group moves together with the second lens group; the third lens group is composed of a positive lens with the convex surface facing the image side and a negative lens disposed away from the positive lens toward the image side and having the concave surface facing the object side; and the positive lens is a double aspherical lens and satisfies predetermined conditions.