The piezoelectric properties of sodium bismuth tantalate Na0.5Bi2.5Ta2O9 (NBTa) dense ceramics were determined using 0.1 wt% Mn-doped samples. The ferroelectric properties of the NBTa ceramics were confirmed. The remanent polarization Pr and coercive field Ec were 15.5 µC/cm2 and 81.5 kV/cm at room temperature, respectively. Optimum poling conditions (temperature Tp, time tp and electric field Ep) were investigated for piezoelectric measurements. The independent electromechanical coupling factors of the NBTa dense ceramics were obtained as follows: kp=10.0, k31=6.1, k33=12.4 and k15=5.6%. These values are comparable to those of the reported bismuth layer-structured ferroelectrics (BLSFs) that are composed of two pseudo-perovskite layers. The physical constants of the NBTa ceramics were also determined. The piezoelectric constants were d33=10.8, d31=5.2, and d15=6.0 pC/N.