A phosphorescent phosphor comprising a matrix expressed by M.sub.1-x Al.sub.2 O.sub.4-x (except X=0) in which M is at least one metal element selected from a group consisting of calcium, strontium and barium. X is in a range -0.33.ltoreq..times..ltoreq.0.60 (except x=0). Europium is doped to said matrix as an activator and at least one element selected from a group consisting of lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium is doped to said matrix as a co-activator. Magnesium is doped to M.