A substrate made of glass serves both as a substrate for a touch panel and as that for a front light, and has both functions of propagating an ultrasonic wave in order to detect a touched position, and propagating light emitted from a light source to guide the light toward a reflective-type liquid crystal display. In the case where an image on the liquid crystal display is made visible by external light, external light which has been transmitted through the substrate is reflected by the liquid crystal display, and the reflected light is again transmitted through the substrate to be emitted from the front face. In the case where the front light function is used, light which has been introduced into the substrate from the light source is reflected by the liquid crystal display, and the reflected light is transmitted through the substrate to be emitted from the front face.