Electric wires are laid down nationwide while they are subject to severe environmental conditions, including natural phenomena, such as heavy wind and rain, and soot and smoke in the industrial area. If water penetrates into an installed wire which is exposed to such an environmental condition, it may accelerate corrosion of wire. If a great amount of stress is applied to a wire, it may result in cracking in the concerned wire section, leading to wire break. In order to ensure reliable power transmission and prevent wire break which causes an accident, it is essential to correctly understand the status of wire corrosion. We propose a new ECT method to inspect high voltage electric wires of common use in Japan and evaluate its practical applicability.