An objective lens actuator, being suitable for a thin-sized optical pickup and a thin-sized optical disc apparatus, comprises: an objective lens for focusing a light upon a recording surface of an optical disc; and a driving means including a focusing coil, tracking coils, and a magnetic circuit, for operating the objective lens into a focusing direction of approaching/receding to/from the optical disc, and into a tracking direction of a radius of the optical disc, wherein the magnetic circuit has two (2) pieces of magnets putting the objective lens therebetween, and one of the magnets is short of length in the focusing direction and is long in length in the tracking direction, comparing to the other magnet, thereby brining an unnecessary moment, which is applied upon a moving part including the objective lens therein, to be small, and suppressing inclination or tile and vibration of the objective lens, so as to deal with high-density and high-speed recording/reproducing of information.