Graphical User Interface (GUI) application component is a compound component, which consists of fine-grained components (such as GUI widgets) and specific logic. GUI application components fabricated by conventional techniques expose low extensibility because of the incomplete separation between the application logic part and GUI part inside the components. In this paper, we propose a new component architecture, "BeaM", which realizes complete separation between both parts inside the GUI application components. We have implemented a development environment corresponding to the proposed architecture in Java language. As a result of experimental evaluations, it is found that BeaM is useful to develop GUI application components as JavaBeans components with high extensibility.