The present invention relates to a nanophosphor and a synthesis method thereof, and provides a nanophosphor comprising a first compound of Formula 1, wherein the first compound is fluoride-based one which is co-doped with Ce3+ and Tb3+. NaGd1−p−q−rMrF4:Ce3+p,Tb3+q (1) In the Formula 1, descriptions on the p, q, r and M are overlapped with what was described in the detailed description of the present invention, so their concrete description are omitted. The nanophosphor has good light emission intensity and magnetic property as well as up-conversion and/or down-conversion property able to emit visible light after excitation by infrared and/or ultraviolet rays, so can be applied to a contrast agent and a counterfeit prevention code.
