A variable power optical system ZL is constructed of, in order from the object side, a first lens unit G1 having a positive refractive power, a second lens unit G2 having a negative refractive power, a third lens unit G3 having a positive refractive power, and a fourth lens unit G4 having a positive refractive power. During variation in power from a wide-angle end state to a telephoto end state, a space between the first lens unit G1 and the second lens unit G2 increases, a space between the second lens unit G2 and the third lens unit G3 decreases, and a space between the third lens unit G3 and the fourth lens unit G4 varies, and a part of the third lens unit G3 is configured to move in directions perpendicular to the optical axis.