A growing root of the higher plant exhibits the spatial pattern and the self-sustained oscillation of the electric potentials near the surface. The electric potential along the root showed a stable banding pattern. This pattern of the electric potential was caused by the transcellular ionic current loops surrounding the root. The phase of the oscillation in the elongation region differed by 180 degrees from those in the mature region and the root tip. The change in the elongation velocity occurred several minutes after the application of the electric field together with the change in patterns of electric potential and pH.