It is an object of the present invention to provide a polycrystalline MgO deposition material which is capable of obtaining a good discharge response characteristic over a wide temperature range. Additionally, it is another object of the present invention to provide a plasma display panel with an improved luminance and a material for the plasma display panel which can remarkably reduce the number of address ICs without lowering the panel luminance. In order to achieve the objects, there is provided an improvement of a polycrystalline MgO deposition material for a passivation layer of the plasma display panel. A characteristic structure is that the polycrystalline MgO deposition material is formed of a sintered pellet of polycrystalline MgO, of which MgO purity is more than 99.9% and relative density is more than 90%. Further, a Si concentration in the polycrystalline MgO is more than 30 ppm and less than 500 ppm.