A variable magnification optical system of reduced size and increased zoom ratio is provided. According to one aspect, a first lens group having a positive refractive power, a second lens group having a positive refractive power disposed to the image side of the first lens group, and a third lens group having a negative refractive power disposed to the image side of the second lens group are provided. When the system goes from a wide-angle end state to a telephoto end state, the first lens group, the second lens group, and the third lens group are moved toward the object in such a manner that a space between the first lens group and the second lens group is increased, and a space between the second lens group and the third lens group is decreased. In this case, a ratio of the focal length of the first lens group to that of the lens system in the telephoto end state satisfies a particular condition.