In this paper, the electrical response of ionic electro-active polymer (IEAP) based tri-layer micro-actuator allowing to consider some phenomena which occur in the micro-actuator behavior is presented. A detailed study on the measured currents during charging and discharging process is analyzed. Electrical charges, time constants, capacitance and resistance of the simplified equivalent electrical circuit are investigated. The results have shown that, the micro-actuator exhibits a linear behavior for applied voltage lower than 1 V. Beyond that, nonlinearities appear and are related to the discharging process, especially the corresponding electrical resistance which increases in a non-linear way. At this stage, accumulated electrical charges which depend on the previously applied voltage are not totally restored during the discharging process. The results of this study are illustrated with experimental and theoretical results.