Carrier injection.. carrier separation, and carrier transport in the films are key processes in organic devices. Therefore, the understanding of interfacial electrostatic phenomena is of crucial importance. From the view point of dielectric physics, we have been studying the surface polarization phenomena. Using Maxwell displacement current (MDC) measurement, optical second harmonic generation (SHG) measurement, and Kelvin-probe surface potential measurement, surface polarization phenomena at the interfaces have been elucidated experimentally and theoretically. This paper describes how the surface polarization phenomena can be clarified by these measurements. Finally, our experiment on evaporated Alq(3) film is shown. (c) 2004 Elsevier B.V. All rights reserved.