Abstract: There are disclosed a europium and terbium-coactivated phosphor having chemical composition formula(M.sub.l-x-y Eu.sub.x Tb.sub.y).sub.n Dwherein M represent Y or Lu, D represents (Al.sub.l-z Ga.sub.z).sub.5 O.sub.12 in which z is defined by 0.ltoreq.z.ltoreq.1, or O.sub.2 S, x is defined by 0.0003.ltoreq.x.ltoreq.0.001, y is defined by 0.0003.ltoreq.y.ltoreq.0.002 and n is 2 or 3, and wherein when D is (Al.sub.l-z Ga.sub.z).sub.5 O.sub.12, M is Y, n is 3 and y is defined by 0.001.ltoreq.y.ltoreq.0.02, or when D is O.sub.2 S, n is 2, y is defined by 0.0003.ltoreq.y.ltoreq.0.005; a cathode ray tube for color copy or color print coated with said europium and terbium-coactivated phosphor; and a copy (printing) unit using said cathode tube.