A zoom lens includes a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a fourth lens unit having a negative refractive power. The first to fourth lens units are arranged in order from the object side to the image side. All of the lens units are moved during zooming from the wide-angle end to the telephoto end. In the zoom lens, a number of lenses in each of the lens units, imaging magnifications on the telephoto end and the wide-angle end of the second lens unit and the third lens unit, a sum of thicknesses on the optical axis of the first lens unit and the second lens unit, and focal lengths of the entire zoom lens at a wide-angle end and at a telephoto end are appropriately set.