Films of ZnO, AlN, LiNbO3, Bi12PbO19, K3Li2Nb5O15, PbTiO3, PZT, Li2B4O7 and Ta2O5 have been fabricated mainly by rf magnetron sputtering. Among these films, the ZnO piezoelectric films have been widely put into practical uses.The AlN films have been also studied along with ZnO films due to its higher ultrasonic velocity, higher electrical resistance and lower film growth temperature.C-axis oriented PbTiO3 films are formed on patterned Pt electrode films imbedded on a SrTiO3 single crystal by a seeded lateral growth.The Sezawa mode propagating in the ZnO film epitaxially sputter-deposited on the R plane sapphire substrate gives a high velocity and high coupling.Piezoelectric and ferroelectric materials are generally optically transparent and electrically insulating, and are useful for electro-, acousto-, and nonlinear optical devices. Then elements made of piezoelectric thin films can be integrated on a Si chip together with electrical integrated circuits.