Maintenance of overhead contact lines should be based on their actual conditions rather than on the length of period in which they have been used. Therefore, we developed a device that detects the deterioration of feeder. As this device requires manual operation, however, we developed a prototype feeder inspection robot. For efficient maintenance of overhead contact line, we have devised an easy inspection of overhead contact lines by closely setting feeder and messenger wires. In this contact overhead line system, there are two feeder messengers. We developed a prototype feeder inspection robot for the two feeder messenger wires and tested it at RTRI.