The resource exchanging is the key function in mobile computing environment. We have the limitation of the capacity for every single mobile device. The only way for efficient use of limited resources is exchanging them each other in mobile environment. In this paper, a mutual resource exchanging model in mobile computing is proposed. Furthermore, two applications of the model are shown. The first one is a universal battery. It enables us to exchange resources of electricity from one to another mobile device. The second application is bandwidth resource sharing among mobile devices. It provides the mobility of bandwidth from devices with surplus network connectivity to other devices that requires more network bandwidth. By this model, flexible and elastic usability can be implemented on mobile devices in mobile computing environment.