By using time-resolved electric field induced optical second harmonic generation (TR-EFISHG) measurement, we studied the electric field distribution change induced in ITO/PI/TIPS-pentacene/Au diodes by carrier injection. Upon application of a step voltage to the diodes, the electric field change across the TIPS-pentacene layer was measured. Significant electric field distribution change was suggested due to the carrier injection, and a simple model that accounts for the I-V characteristics of the diodes was proposed, on the basis of the Maxwell-Wagner model analysis. The TR-EFISHG measurement is very helpful for studying the device performance in terms of carrier injection. (C) 2013 Elsevier B. V. All rights reserved.