1. A method for extracting a shape variation descriptor in order to retrieve content-based image sequence data that express motions of an object, comprising the steps of: (a) selecting a predetermined number of the frames from the image sequence data; (b) transforming the frame into an object frame including information about only the object that is separated from a background of the frame; (c) aligning the object into a predetermined location of the frame and generating an aligned frame; (d) superposing a number of the aligned frames so as to generate one frame, that is, a shape variation map (SVM) including information about motions of the object and information about shapes of the object; and (e) extracting the shape variation descriptor with respect to one SVM.