Piezoelectric/electrostrictive ceramics having the composition represented by the general formula: xBNT-yBKT-zBT (x+y+z=1) are provided, wherein at least one kind among A-site elements are allowed to become deficient from stoichiometry in which a point (x, y, z) representing content ratios x, y and z of (Bi1/2Na1/2)TiO3, (Bi1/2K1/2)TiO3 and BaTiO3 is within a range including a border line of a quadrangle ABCD with a point A, a point B, a point C and a point D as vertices in a ternary phase diagram. Vacancies are formed in an A-site of a perovskite structure by allowing the A-site elements to become deficient from stoichiometry. An amount of A-site vacancies becomes at least 2 mol % to at most 6 mol %.