White LEDs based on near ultraviolet LED and red/green/blue phosphors have been attracted in terms of outstanding color rendering index. In particular, we focus on the blue emitting phosphors because the commercial BaMgAl10O17:Eu2+ needs high temperature in order to be obtained. In this study, we succeeded in synthesizing Eu2+-activated Na2Mg2Si6O15 phosphors as a single phase by the conventional solid state reaction. Eu2+-doped Na2Mg2Si6O15 phosphors showed the broad blue emission from 400-550 nm due to the 4f-5d allowed transition of Eu2+ under the ultraviolet light excitation. Moreover, the emission intensity of Eu2+-activated Na2Mg2Si6O15 phosphor at high temperature kept about 85% at 423 K, which indicated the thermal stability of Na2Mg2Si6O15:Eu2+ was extremely higher than that of other Eu2+-activated silicate phosphors. Thus, Eu2+-activated Na2Mg2Si6O15 phosphor is able to become the novel luminescent material for White LED based on the near-ultraviolet LED.