Development of a transom stern form design method is tried as a practical application of results of our studies on transom stern until now. As a result, a method is proposed. Its characteristic points are: 1) Three factors which are deeply related with stern wave resistance are selected as factors to represent transom stern form. 2) The method can treat also transom stern of such ship whose draft at out-ward voyage is different from that at home-ward voyage. Model tests to get necessary data for the method and an example of design by the method are also shown.