A complex halide phosphor represented by the following composition formula and an X-ray image converter using the same: (Me.sub.1-f,Mg.sub.f )F.sub.2.aMe' X.sub.2.bKX'.cMe" SO.sub.4 :dEu.sup.2+,eTb.sup.3+wherein Me, Me' and Me" each represents at least one of the alkaline earth metals of the group consisting of barium, strontium and calcium; X and X' each represents at least one of chlorine and bromine; and a, b, c, d, e and f are numbers defined by one of the following five combinations:1. 0.80.ltoreq.a.sub.1 .ltoreq.1.50, 0.10.ltoreq.b.sub.1 .ltoreq.1.50, c.sub.1 =0, 0.001.ltoreq.d.sub.1 .ltoreq.0.20, e.sub.1 =0 and f.sub.1 =0.2. 0.30.ltoreq.a.sub.2 .ltoreq.1.50, 0.10.ltoreq.b.sub.2 .ltoreq.2.00, 0.01.ltoreq.c.sub.2 .ltoreq.1.00, 0.001.ltoreq.d.sub.2 .ltoreq.0.20, e.sub.2 =0 and f.sub.2 =0.3. a.sub.3 =1, b.sub.3 =0, c.sub.3 =0, 0.01.ltoreq.d.sub.3 .ltoreq.0.10, 0