a room occupancy monitoring system monitors the occupancy status of a plurality of rooms and collects and displays the room occupancy information in real time . the room occupancy monitoring system includes a plurality of room occupancy sensor devices and a server . each of the room occupancy sensor devices is located in a corresponding one of a plurality of rooms , detects whether the corresponding one of the plurality of rooms is occupied , and generates a first signal indicating whether the corresponding one of the plurality of the rooms is occupied and a second signal indicative of the identity of the corresponding one of the rooms . the server receives the first signal and the second signal from the room occupancy sensor devices through a data communication network and displays room occupancy information of the plurality of the rooms based on the first signal and the second signal on a display device .