A highly transparent barrier rib was investigated for use in a transparent ac plasma display panel. SU-8 photoresist is an appropriate material for a highly transparent barrier rib because it absorbs only a small amount of light and provides a simple fabrication method for a rectangular barrier rib. SU-8 photoresist barrier rib had a problem with reliability because it can be damaged by the plasma. Therefore, a silicon dioxide layer covered the SU-8 photoresist barrier rib for protection. Using this method, we obtained a highly transparent barrier rib with a long lifetime and a transmittance level of approximately 90%.