Using Electrochemical Impedance Spectroscopy (EIS), in the tribocorrosion field, especially in fretting corrosion, is new. The key point of this work is using EIS. The influence of ionic strength (I_c) and a model protein, albumin, on passive layer behavior was studied. At cathodic applied potential, E=−400 mV(SCE), fretting leads to an increase of corrosion current, without albumin. The current drop increases with the ionic strength. With albumin of 20 g L⁻¹, I is constant whatever the ionic strength: albumin acts as a corrosion inhibitor. Thanks to EIS, the degradation of passive layer due to fretting-corrosion is assessed by the fall of Polarization Resistance (R_p) and exponent of constant phase element (n), and the rise of constant phase element (Q).