A zoom lens has, in order from the object side thereof, a positive first lens unit G1, a negative second lens unit G2 and a rear group having a positive refracting power and composed of at least one lens unit. The lens unit located closest to the object side in the rear group is a third lens unit G3. An aperture stop S is provided at a position closer to the image side than the second lens unit G2 and closer to the object side than the lens surface located closest to the image side in the third lens unit.