An optical information recording/reproducing apparatus for optically writing and reproducing information on a disk-shape recording medium according to the present invention includes: a base; an objective lens for converging a light beam on the disk-shape recording medium, an optical axis of the objective lens being perpendicular to the disk-shape recording medium; an actuator for actuating the objective lens along an optical axis direction in which the optical axis of the objective lens extends and along a radial direction of the disk-shape recording medium, wherein the actuator is fixed on the base and includes a lens holder for supporting the objective lens, and a first electrokinetic type transducer and a second electrokinetic type transducer for driving the lens holder along the optical axis direction and/or the radial direction of the disk-shape recording medium, the first and second electrokinetic type transducers interposing the lens holder, and a distance between the first electrokinetic type transducer and the base being different from a distance between the second electrokinetic type transducer and the base; and an optical member for directing a light beam to travel between the first electrokinetic type transducer and the base and to be incident on the objective lens.