In an industrial plant, straight piping, vertical piping, curved piping, valves, and flanges are arranged in complex patterns. Problems regarding automated pipe inspection originate in the fact that sensors cannot scan complex piping schemes involving flanges, valves, curved piping, and vertical piping. Various types of pipes are used in industrial applications, taking into consideration the temperature and the corrosive properties of the fluid. Oil plants, for example, use mainly carbon steel, stainless steel, and chloridized vinyl pipes. In light of this, we have focused on developing a robot that can inspect carbon steel pipes, having the ability to move automatically along the outside of a length of piping. This paper describes the structure of magnetic wheels used in a pipe inspection robot. We propose a robot that has a mechanism consisting of wheel-type magnets. Using the power generated by the magnets, the robot maintains its attachment to the pipe. The mechanism of the robot is composed of three units, and is able to automatically inspect a pipe's surface, traverse flanges, and rise along vertical piping. To achieve the robot's optimum performance, the design of the magnetic wheels is important. The authors have previously designed a similar robot composed of three connected units, though the adherence power of this robot was weak and could not achieve a high level of stability while advancing along a straight length of pipe.