A zoom lens includes, in order from an object side to an image side, a first lens unit of positive refractive power, a second lens unit of negative refractive power, a third lens unit of positive refractive power, a fourth lens unit of positive refractive power and a fifth lens unit of negative refractive power, wherein, during zooming from a wide-angle end to a telephoto end, at least the first, third, fourth and fifth lens units are axially moved toward the object side in such a manner that a separation between the first lens unit and the second lens unit increases and a separation between the second lens unit and the third lens unit decreases, and wherein the fifth lens unit is axially moved toward the image side to effect focusing on from an infinitely distant object to a closest object.