The present invention provides a protecting film capable of preventing deterioration in adhesion and matching to a substrate (dielectric layer), and deterioration in electric insulation. The protecting film includes a film body composed of MgO or the like which is inhibited from reacting with CO2gas and H2O gas in air to prevent degeneration of MgO or the like into MgCO3and Mg(OH)2, etc. harmful to FPD. The film body is formed on the surface of the substrate, and the fluoride layer is formed on the surface of the film body. The fluoride layer is represented by MOXFY(M is Mg, Ca, Sr, Ba, an alkali earth complex metal, a rare earth metal, or a complex metal of an alkali earth metal and a rare earth metal, 0≦X<2, and 0
