A compact zoom lens includes a first lens unit disposed closest to an object side, an aperture, and a rear lens group. The first lens unit includes a first diffraction optical part having positive refractive power, and the rear lens group includes a second diffraction optical part having positive refractive power. The power relation between the two diffraction optical parts and the positions of the diffraction optical parts are set appropriately. The zoom lens can have a high zoom ratio wherein chromatic aberration is fully corrected, and an image pickup apparatus employing this zoom lens can be provided.