The invention provides an internally illuminated sign comprising an information display section having at least one flat or curved surface which retroreflects light coming from the front of said sign and transmits light from the interior of said sign; an illuminator disposed behind the information display section; and a housing which encloses and holds said information display section and the illuminator. Those retroreflective elements used in said information display section are prismatic retroreflective elements according to the principle of total internal reflection, a large number of which are densely arranged to form a continuous retroreflective plane, at least the retroreflecting area of the back of said large number of prismatic retroreflective elements has no bonded area to other layer(s).