A novel stimulable phosphor having a high sensitivity to a semiconductor laser as a stimulating light is disclosed, and is represented by the formula:{(M.sup.II X.sup.1.sub.2-2u X.sup.2.sub.2u).sub.1-x-y (M.sup.I X.sup.1.sub.1-v X.sup.2.sub.v).sub.x (M.sup.III X.sup.1.sub.3-3w X.sup.2.sub.3w).sub.y }.sub.1-a A.sub.a :bEu.sup.2+where M.sup.II represents at least one divalent metal such as Ba, Be, Mg or Ca; M.sup.I represents at least one monovalent metal such as Li, Na, K, Rb or Cs; M.sup.II represents at least one divalent metal such as Ba, Be, Mg or Ca; M.sup.III represents at least one trivalent metal such as Sc, La, Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga, In or Tl; X.sup.1 represents Br or Cl; X.sup.2 represents at least one halogen atom that is different from X.sup.1 ; A represents at least one metal oxide such as BeO, MgO, CaO, SrO, BaO, Al.sub.2 O.sub.3, Y.sub.2 O.sub.3, La.sub.2 O.sub.3, In.sub.2 O.sub.3, Ga.sub.2 O.sub.3, SiO.sub.2, TiO.sub.2, ZrO.sub.2, GeO.sub.2, SnO.sub.2, Nb.sub.2 O.sub.5, Ta.sub.2 O.sub.5 and ThO.sub.2 ; and wherein 0.ltoreq.x+y.ltoreq.0.5; 0.ltoreq.u+v+w.ltoreq.0.1; 0.ltoreq.a.ltoreq.0.1; and 0.ltoreq.b.ltoreq.0.2.