At least one exemplary embodiment is directed to a zoom lens includes a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and an image-side lens unit in order from an object side to an image side wherein an interval between the first lens unit and the second lens unit varies during zooming, the first lens unit includes an optical element having a positive refractive power and made of a solid material having an Abbe number (.nu.d) and a relative partial dispersion (.THETA.gF) satisfying the following conditions: 0.755.THETA.gF-(-1.665.times.10.sup.-7.nu.d.sup.3+5.213.times.10.sup.-5.n- u.d.sup.2-5.656.times.10-3.nu.d)<1.011 and 1.6<(ft/f1).sup.2<5.6, wherein f1is the focal length of the first lens unit and ft is the focal length of the zoom lens at a telephoto end.