Computers and software are now widely used in human society. With their dissemination, it becomes necessary for disabled and elderly people to use software. However, it is difficult to develop accessible software for them. Also, there are many guidelines and support tools for developing accessible web sites. However, for software, such guidelines and support tools are few. In our research, to develop accessible software easily, we propose a method of evaluating the accessibility of Graphical User Interface (GUI) software. In our method, source programs of GUI software are analyzed, the accessibility of the GUI software is evaluated along with the accessibility guidelines, and the list of unsatisfactory codes for accessibility and indications on how to modify them are shown.