Abstract: The TS panel can be easily observed with the traffic signal. Multiple pieces of information are changed over to be displayed on the TS panel, and a luminescent color of the information such as traffic condition reports, traffic slogans, advertisements, etc. or a luminescent color of the background of the information is illuminated in the same color as that of a the turned-on light of the signal. A detector detects whether each lamp is turned on or not without modifying an electric circuit of the signal. Then, multiple pieces of information are sequentially changed over in synchronism with a changeover of a turned-on color of the signal in accordance with a detection signal output from the detector, and the luminescent color of the background is changed over to be of a color which is the same color as that of the light currently turned on. As a result, various information can be displayed on the TS panel, and a signal color can be recognized not only by a signal lamp but also a display color of the TS panel.