The pitch of wiring on printed circuit boards has become finer for the development of small and lightweight electronic devices. There is a risk of breaking the wiring due to slight corrosion since the pitch of wring becomes finer. A sensor to monitor dew condensation and corrosion of wiring must be developed for preventing these corrosion phenomena. Our group 1,2) developed a corrosion monitoring sensor fabricated by screen printing. This sensor has a silver wiring of comb-shape on plastic sheet. Monitoring of dew condensation environment was conducted by using electrochemical impedance spectroscopy (EIS) because EIS allows information of condensation state from change of impedance. In this study, oxidation rate of silver was monitored by a screen-printed comb-shape wiring sensor. In addition, we developed a portable sheet-type counter electrode with thin gel electrolyte. Qualitative and quantitative analysis for corrosion products on silver wiring was carried out with this portable electrode after the corrosion monitoring, and Ag2S, Ag2O and AgCl were detected.References I. Shitanda, A. Okumra, M. Itagaki, K. Watanabe, Y. Asano, Sensor Actuat B-Chem, 139, 292 (2009).A. Aiba, N. Fujii, Y. Hoshi, I, Shitanda, M. Itagaki, J. Electrochem, Soc., 165, C743 (2018).