A variable magnification optical system comprises, in order from an object side: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; a fourth lens group having positive refractive power; and a fifth lens group; upon varying magnification from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group, a distance between the second lens group and the third lens group, a distance between the third lens group and the fourth lens group and a distance between the fourth lens group and the fifth lens group being varied, the fifth lens group being moved with respect to the image plane; upon focusing the third lens group being moved along the optical axis; and the given conditional expressions being satisfied; thereby providing a small-size variable magnification optical system having a high variable magnification ratio and an excellent optical performance.