An image display system is disclosed. The image display system includes an image display device forming an image and a mobile terminal device supplying image information to the image display device over a predetermined network, wherein the image display device includes: a storage unit which stores connection information for connecting to the image display device in the predetermined network; an encoding unit which encodes connection information code including the connection information; and a display unit which displays the connection information code or an image including the connection information code, and wherein the mobile terminal device includes: a code acquiring unit which acquires the connection information code from the displayed connection information code or the image including the connection information code; a code analysis unit which analyzes the connection information from the acquired connection information code; and a network connection establishment unit which establishes network connection with the image display device on the basis of the analyzed connection information.