A security system including several camera devices and a communication device in sites at which monitoring is required by a user. The several camera devices may constantly monitor the sites. The camera devices have motion detecting functions and provide unusual status reporting signals and necessary image information to the communications device when the movements of an intruder have been detected. The communication device communicates with and is connected to a server that serves as an information center via the internet line when unusual status signals have been received. The information from the camera devices is also sent to server. The server automatically notifies the user by a predetermined user-selected method. The notified user can access the server and confirm the information.