The effects of the addition of La2O3 (0.1 wt. %−1 wt. %) and MnO2 (0.1 wt. %−1 wt. %) on the piezoelectric properties of the 0.02Pb(Y2/3W1/3)O3−0.98Pb(Zr0.52Ti0.48)O3 system were investigated to develop the composition available for an actuator. In the case of the addition of La2O3 to the system, the maximum values of d33 and kp were observed in the 0.1 wt. % La2O3, and the values of Qm did not change with the amount of La2O3. The values of d33, kp, and Qm were 428 × 10−12 C/N, 57%, and 71, respectively. On the other hand, the introduction of 0.5 wt. % MnO2 as an acceptor into the system resulted in the maximum Qm value of 741, exhibiting a d33 of 298 × 10−12 C/N, and a kp of 50%. In the case of the simultaneous addition of La2O3 and MnO2, the best piezoelectric properties are obtained from the composition of 0.02Pb(Y2/3W1/3)O3−0.98Pb(Zr0.52Ti0.48)O3 + 0.1 wt. % La2O3 + 0.3 wt. % MnO2. The values of d33, kp, and Qm were 345 × 10−12 C/N, 55%, and 741, respectively.