Abstract: Provided is a terminal node device including: a communication module communicating with an external sink node device and another terminal node device; sensor modules; and a control unit allowing the terminal node device to be operated while allowing the terminal node device to transition into one of the initial, synchronous, and leave states. In the initial state, the control unit scans a received message; if a beacon message is received from a sink node device, the control unit transitions into the synchronous state; and if not for a predetermined time, the control unit transitions into the leave state. Accordingly, if a beacon message is received from the sink node device, the terminal node device transitions into the synchronous state to constitute a server-based wireless sensor network; and if not, the terminal node device transitions into the leave state to constitute an independent sensor network.