A device that can detect both DC and AC components of the bioelectric signal is proposed. The device consists of modified DC servo circuit and can measure the sympathetic skin response(SSR)noninvasively with plate electrodes. We conducted experiments for 5 subjects by stimulating the subjects with sound or electric stimulation to induce the SSR, and recorded the SSRs with the device from the forearm, palm, crus and sole. The results showed that the device could detect stable signal of both DC and AC components of SSR. Though duration of the SSR estimated from AC component has been reported to be around 5s, the recordings of DC component of the SSR revealed that SSR has 10 times longer duration. In addition, we calculated latency differences between forearm and palm, and also between crus and sole in order to derive the nerve's conduction velocity. The estimated nerve's conduction velocity was 0.76m/s on the average and this result agreed with physiological data of the conduction velocity of autonomic ganglia's fiber, 0. 3-1. 0m/s.
