To solve such problems that, in a wall climbing robot conducting the adsorption running on the vertical wall, a frame body and a wall face cannot maintain a parallel state because of the rotation moment with own weight to cause adsorption exfoliation from the wall face when running and a wall face running speed becomes slow since the moving interval of an upper and lower adsorption pad cannot be made large to achieve stable running.

A rotational moment offset mechanism 4 is provided which biases the lower end part of the robot frame body 2 to the opposite direction of the wall face, and an expanding and contracting mechanism for a stepped surface is provided which changes the height with the wall face in the adsorption pad according to the step difference. Thereby, the frame body 2 and the wall face can maintain a parallel state, the moving distance of the adsorption pad is lengthened, and the moving speed is accelerated to two times the frame body moving speed.