Electron holography was carried out extensively to analyze the electric field around a single TaSi2 nanowire with applied voltage and to visualize the lines of magnetic flux of Fe3O4 nanowires. In the electric field analysis, the electric potential distribution between the TaSi2 nanowire and anode was clearly visualized with an increase in the applied voltage. During the field electron emission condition, the equi-electric potential lines were blurred, which has been considered to result from the fluctuation of the electric potential between the nanowire and anode due to the field electron emission. In the magnetic field analysis, the lines of magnetic flux were basically parallel to the longitudinal direction of Fe 3O4 nanowires, indicating that the shape anisotropy was significant in the magnetization distribution in these nanowires. In addition, the observation revealed the presence of a magnetic interaction between the neighboring nanowires. copyright The Electrochemical Society.