The phosphor to be measured was pulverized up to a predetermined average particle size (preferably 1.0 ??m to 20.0 ??m) by using pulverizing means such as the mortar and the ball mill after firing, and a holder made of titanium was filled with the phosphor thus pulverized to form a flat surface, then the phosphor was measured by an XRD apparatus, ???RINT 2000??? by RIGAKU DENKI CO., LTD. Measureme