The high-power piezoelectric characteristics of (Bi_0.5Na_0.5)TiO₃ (BNT)-based solid solutions at a high temperature (~130°C) were studied, by comparing them with those of hard Pb(Zr,Ti)O₃ (PZT) ceramics. The vibration velocity v_0-p of the BNT-based ceramics was stable as the temperature increased to 130°C, whereas that of the PZT-based ceramics markedly decreased with increasing temperature. It is generally known that the stability of v_0-p under high-amplitude vibration is related to mechanical losses caused by domain wall motion. Therefore, the temperature dependence of the mechanical quality factor Q_m of these ceramics was measured by electric transient response measurement. The measured Q_m values of the BNT-based ceramics were nearly constant or slightly decreased with increasing temperature, whereas Q_m for the PZT ceramic markedly decreased with increasing temperature.