Giant electric-field-induced strain of 0.70%, corresponding to a d(33)* value of 1400 pm V-1, is observed in a lead-free (Bi1/2Na1/2) TiO3-based polycrystalline ceramic. This is comparable to the properties of single crystals. An in situ transmission electron microscopy study indicates that the excellent performance originates from phase transitions under the applied electric fields.