Displacement current measurement (DCM) is widely used as a method for analyzing carrier behaviors of organic devices. Carrier behaviors are analyzed using transient currents. On the other hand, electric-field-induced optical second-harmonic generation (EFISHG) measurement is capable of directly probing carrier motions in organic devices, where the migration of electric field stemmed from carriers is measured. In this study, we employed the DCM and EFISHG measurements for analyzing interfacial carrier behaviors in Au/pentacene/polyimide (PI)/indium-tin-oxide (ITO) double layer organic devices, where interfacial accumulated charges and electric fields formed in the pentacene layer were explored.