The mobile structure tracking device includes processing circuitry. The processing circuitry acquires point cloud data comprising a plurality of feature points obtained by ranging a surrounding environment including another ship with respect to an own ship, sets individual areas for the plurality of feature points based on a distribution of positions of the plurality of feature points, selects the target tracking ship based on the size of the individual areas, and generates tracking data based on a time-series change of the positions of the target tracking ship.