The doping effect of various rare-earth metals on electric field strains was investigated in (Pb,Ba) (Zr,Ti)O3 ceramics. The ceramics doped with La, Ce or Pr, whose ionic radius is larger than that of Nd exhibited soft piezoelectric properties. The ceramics doped with Dy, Gd, Er, or Y of smaller ionic size showed hard piezoelectric characteristics. The induced strain was greatest around the boundary samples between the soft and hard types. The maximum strain under an electric field of 1 kV/mm reached up to 0.13% for the ceramics doped with Nd. The dependence of the electric field induced strain on the doping amount and temperature has also been investigated.