Disclosed herein are a sintered magnesium oxide material which is capable of suppressing the occurrence of splashing during film formation and which is less likely to cause clogging of a supply inlet of a film formation device, a deposition material for PDP-protecting film using the same, and a process for producing the sintered material. The sintered magnesium oxide material contains magnesium oxide, 3 to 50 mass % of an oxide of a Group 2A element other than magnesium in the periodic table, and if necessary, 1000 ppm or less of one or two or more elements selected from the group consisting of aluminum, yttrium, cerium, zirconium, scandium, and chromium, and has a disk-like, elliptical plate-like, polygonal plate-like, or half-moon-like shape or a cubic or rectangular solid shape with rounded apexes.