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 positive refractive power. The first and third lens units are movable such that they are located closer to the object side at a telephoto end than at a wide-angle end. The fourth lens unit is movable with a locus convex towards the object side. A distance between the first and second lens units at the telephoto end, a distance between the second and third lens units at the telephoto end, a focal length of the first lens unit, a focal length of the second lens unit, and a focal length of the third lens unit, and a focal length of the entire zoom lens at the wide-angle end are appropriately set.