A zoom lens system includes, in order from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having positive refractive power, a fourth lens unit having positive refractive power, and a fifth lens unit. When the lens positions change from the wide-angle end to the telephoto end, at least the first to fourth lens units are movable in an optical axis direction. The fifth lens unit includes a negative subunit having negative refractive power and a positive subunit having positive refractive power and being disposed on the image side of the negative subunit with a predetermined air gap the negative subunit and the positive subunit, and is capable of shifting the image by shifting the positive subunit in a direction substantially orthogonal to the optical axis.