The displacement currents of 8A5H were varying barrier speeds. The magnitudes of displacement currents were increased when the positive direction at the compressing mode but speeds of the compressing barrier were increased. And the displacement current of 8A5H flowed into they flowed into negative direction at the expansion of barriers. The changes of the pressure area isotherms of 8A5H were obtained when UV light (360[nm]) and visible (450[nm]) light were irradiated alternatively. From these measurements, structural changes of molecules on the air-water interface were certified. And, the displacement currents which were induced by photoisomerization were measured.