A zoom lens includes, in order from an object side to an image side, a positive first lens unit, a negative second lens unit, an aperture stop, a positive third lens unit, and a positive fourth lens unit. The third lens unit includes, in that order, a positive first lens sub-unit, and a negative second lens sub-unit. The second lens sub-unit is movable in a direction having a component perpendicular to an optical axis to change an image forming position in a direction perpendicular to the optical axis. A distance on the optical axis between the aperture stop and the third lens unit at a wide-angle end, a composite focal length of the first lens unit and the second lens unit at the wide-angle end, a focal length of the first lens sub-unit, and a focal length of the second lens sub-unit are appropriately set.