A high-precision positioning apparatus includes a fine driving unit for producing horizontal and small movements of a flat recording medium relative to an optical system, the medium being used for optically recording and reproducing information. The fine driving unit includes a frame-shaped unit body, a first driving frame inside the unit body, and a second driving frame inside the first driving frame and secured at a position adjacent to a magnetized portion of the recording medium. The first driving frame is movable relative to the unit body by fine driving devices in the horizontal direction of the recording medium, while the second driving frame is movable relative to the first driving frame by other fine driving devices in the horizontal direction of the recording medium and in the direction substantially orthogonal to the moving direction of the first driving frame, thereby producing horizontal and small movements of the recording medium.