As a method of observing regeneration of damaged nerves, research is being conducted on analyzing the electric signals of nerve fibers that are damaged and regenerating by implanting a microelectrode array between those nerves. Microelectrode arrays possess high impedance and a unique phase characteristic according to their structural features, thus it requires a phase linearity test and an impedance test to prevent neural signal distortion. Therefore, this paper analyzes the features of microelectrode array and designs a bioamplifier. We also measured signals from sciatic nerves in rats with microelectrode array.