An object is to provide a zoom lens system with a high zoom ratio capable of preferably correcting aberrations with securing sufficient amount of back focal length by well-suited power arrangement. The zoom lens system includes, in order from an object, 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 negative refractive power, and a fifth lens group having positive refractive power. When zooming from a wide-angle end state to a telephoto end state, a distance between the first and the second lens groups increases, a distance between the second and the third lens groups decreases, a distance between the third and the fourth lens groups increases and a distance between the fourth and the fifth lens groups decreases. A given conditional expression is satisfied.