For possible applications as luminescent materials for white-light emission using UV-LEDs, Ba2Mg(PO4)2:Eu2+ phosphors were prepared by a solid state reaction. The photoluminescence properties of the phosphor were investigated under ultraviolet ray (UV) excitation. The prepared phosphor powders were characterized to from a single phase of a monoclinic crystalline structure by a powder X-ray diffraction analysis. In the photoluminescence spectra, the Ba2Mg(PO4)2:Eu2+ phosphor showed an intense emission band centered at the 584 nm wavelength due to the f-d transition of the Eu2+ activator. The optimum concentration of Eu2+ activator in the Ba2Mg(PO4)2 host, indicating the maximum emission intensity under the excitation of a 395 nm wavelength, was 5 at%. In addition, it was confirmed that the Eu2+ ions are substituted at both Ba2+ sites in the Ba2Mg(PO4)2 crystal. On the other hand, the critical distance of energy transfer between Eu2+ ions in the Ba2Mg(PO4)2 host was evaluated to be approximately 19.3 A. With increasing temperature, the emission intensity of the Ba2Mg(PO4)2:Eu phosphor was considerably decreased and the central wavelength of the emission peak was shifted toward a short wavelength.