A fluorescent composition capable of emitting light of various luminous colors under electron or ultraviolet excitation and a fluorescent luminous device having mounted such a fluorescent composition mounter therein. The fluorescent composition has a general formula of ZnO.Ga.sub.2 O.sub.3 and emits light of a luminous spectrum distributed at an ultraviolet or visible region. The fluorescent composition includes a matrix of ZnO.Ga.sub.2 O.sub.3 and Cd doped in the matrix. The fluorescent luminous device includes at least one ZnO.Ga.sub.2 O.sub.3 :Cd phosphor deposited on anode conductors and at least one luminous display section having an ultraviolet excitable visible light emitting phosphor deposited thereon within a region of radiation of ultraviolet rays emitted from the ZnO.Ga.sub.2 O.sub.3 :Cd phosphor.