Two topics on the recent structural studies of perovskite-type ferroelectrics under applied electric field are introduced. One is on the time-course measurement associated with the polarization reversal in a BaTiO3 single crystal capturing the change in lattice strain of millionths of a second. The other is on the electric field induced large lattice-strain in pseudocubic Bi(Mg1/2Ti1/2)O3-modified BaTiO3-BiFeO3 lead-free piezoelectric ceramics. Both experiments are carried out at SPring-8.