This paper shows that the electrochemical mass transport in polypyrrole (Ppy) thin film deposited electrode, involves the rheological change and electrochromatics of the Ppy. These changes can be detected by measuring the resonant frequency, resonant resistance, and UV spectrum of a Ppy deposited quartz crystal. A Ppy deposited quartz crystal is used and measured the cyclic voltammograms in KClO4 electrolyte solution. The changes of the resonant frequency and resonant resistance showed that mass trasport and viscoelastic changes occur in the Ppy film. The absorption change means that the electrochromatics change occurs also in the Ppy film.