Smart-phone market is rapidly growing. Various smart-phones are arousing much interest of people. We can find many different smart-phone applications which are successfully applied to everyday life. However, it is not easy to find presentation applications that integrate PCs, USB memories and smart-phones with wireless network. The application we developed constructs a kind of client-server environment of a PC and multiple smart-phones with Wi-Fi. It allows presenters not only to control the connected remote PC but also to transfer files from PC to smart-phone and vice versa. The smart-phone of the functions takes the roles of USB memories and remote presentation controllers. Moreover, a new Q&A function was built in the application to support more effective Q&A communication between presenters and audience that is not possible to be implemented under the conventional presentation environment. With it, audience can register their questions even while presentation is on.