A data handling apparatus is provided which includes a rotatable disk provided with at least an innermost track and an outermost track for storing data, and a disk cartridge for housing the disk. The disk cartridge is formed with an opening for exposure of a portion of the disk. The opening is substantially symmetrical with respect to a first center line extending radially of the disk. The data handling apparatus also includes a slider floatable relative to the disk, and a driving mechanism for moving the slider relative to the disk along a transfer path. This transfer path and the first center line of the opening are arranged to be non-parallel to each other.