(Bi0.5Na0.5)0.94Ba0.06TiO3 (BNBT-6) with simultaneous addition of 0.5 mol% CeO2 and 0.25, 0.5 and 0.75 mol% La2O3, respectively, was prepared by a conventional ceramic fabrication technique. An addition of 0.5 mol% CeO2 together with 0.5 mol% La2O3 enhanced the piezoelectric and dielectric constant of BNBT-6 ceramics significantly. At room temperature, this composition exhibits a high piezoelectric constant (d33=162×10-12 C/N) and relatively low dielectric loss (cosδ=2.0%) at 1 kHz. X-ray diffraction pattern shows that the coexistence of tetragonal and rhombohedral phases in the BNBT-6 composition was not changed by adding CeO2+La2O3, and they diffused into the BNBT lattice during sintering. SEM observation indicates that a small amount of CeO2+La2O3 almost does not affect the microstructure.