PROBLEM TO BE SOLVED: To reduce the size and weight of a focusing lens group, achieve high-speed focusing and quietness at the time of focusing without increasing the size of the lens barrel, and further change the magnification from the wide-angle end state to the telephoto end state. Provided is a variable magnification optical system that satisfactorily suppresses aberration fluctuations during time and aberration fluctuations during focusing from an infinity object to a short-range object. SOLUTION: A variable magnification optical system has a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens having a positive refractive power in order from the object side. It has a group G3 and a fourth lens group G4 having a negative refractive power, and the distance between the first lens group G1 and the second lens group G2 changes at the time of magnification change, and the second lens group G2 and the third lens group G2 The distance from the lens group G3 changes, the distance between the third lens group G3 and the fourth lens group G4 changes, and the fourth lens group G4 moves at the time of focusing to satisfy a predetermined conditional expression. [Selection diagram] Fig. 1
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