In this work, the in-situ viscoelastic characteristics of electropolymerized polypyrrole(Ppy) thin film were investigated under various electrolyte solutions, NaCl, NaClO₄, NaNO₃, and NaDS using quartz crystal analyzer(QCA). An Ag/AgCl electrode was used as a reference electrode, and a Pt electrode was used as a counter electrode, and an aqueous solution of 0.1 M KClO₄ was used as an electrolyte. One side electrode of quartz crystal was used as a working electrode coupled with specially fabricated QCA electrochemical cell. The resonant frequency and resistance diagram(F-R diagram) was used to interpret the results and compared with AFM photograph. The resonant frequency, resonant resistance, and current were measured when the cyclic voltammetry was performed using galvanostatically polymerized Ppy film coated ATcut quartz crystal electrode. As the size of an anion is larger, the viscoelastic change was more prominent due to the anion doping and electrolyte solution penetrating into the polypyrrole thin film.