We report electrical impedance measurements of organic electroluminescent (EL) devices consisting of ITO/blended emitting layer/LiF/Al. The measured impedance data have single semicircles, therefore, the equivalent circuit represented by a parallel combination of bulk resistance, R-b and capacitance, C-b, in series with a resistance, R-a. There is no interfacial capacitance, suggesting that LiF layer did not affect the charge injection of the organic EL device.