In this review, we discuss the Maxwell-Wagner (MW) effect model analysis of organic devices and time-resolved optical second harmonic generation (TR-EFISHG) measurement that is available for directly probing carrier motion in organic semiconductor devices. Using these, we show that organic field effect transistor as well organic double-layer device operation is analyzed well, and we can make clear the mechanism of these organic devices' operation. Finally, we conclude that the dielectric physics approach using the MW model analysis and the TR-EFISHG experiment is useful to study carrier transport mechanism of organic devices.