In this paper, we propose a system for estimating the concentration of biochemical reagents through impedance measurement. In particular, we studied electrode structures that can accurately measure impedance. We have fabricated electrodes using printed circuit boards (PCBs), tapes, plastic films, and copper tapes applicable to existing mass production facilities and investigated their performance. When the PCB pattern includes a pair of electrodes, a tape or plastic film is used to make a well to hold the reagent. On the other hand, when two pieces of copper tape were used, a hole in one piece acts as a well. The performances of various electrode structures were compared by obtaining the coefficient of variation in the measurement through repeated measurements of the impedances of various saline solutions of known concentrations. Experimental results show that the impedance of a reagent can be measured stably using copper electrodes.