A new nitric oxide (NO) selective electrode was developed. The tip diameter of the NO electrode is less than 10 pm. A working and a reference electrodes are located coaxially at the tip of the NO electrode. A stable NO donor SNAP (S-nitroso-N-acetyl-DL-penicillamine) and a putative NO scavenger hemoglobin (Hb) was used to examine the response of the electrode. Considering the instantaneous concentration of NO secretion previously reported in biological systems, 0.1, 1 pM NO solution was used to calibrate the electrode. From the result of the test of the electrode with SNAP and Hb, we confirmed this microcoaxial NO electrode can detect NO released from SNAP directly and continuously. From the result of calibration of the electrode, good linearity was examined in sub-molar concentration range. It is expected to detect local NO concentration in biological systems with a high space resolution.