1. A region data describing apparatus for describing information of a moving object region in a video sequence, the apparatus comprising: a first describing unit configured to describe time data including a start time and a duration time of the object region in the video sequence; a second describing unit configured to describe type data being an integer, the type data specifying a type of figure, corresponding to the object region, the integer also specifying a number of vertices of the figure; and a third describing unit configured to describe figure data specifying a trajectory of at least one of the vertices, the figure data including: time arrangement data including times of points used to determine the trajectory, key value data representing values of the points used to determine the trajectory, and function data for indicating the trajectory of at least one of the vertices using a function identifier, the function identifier indicating an order of a function used to determine the trajectory or indicating that no function is defined to determine the trajectory.