Construction work on steep slopes is difficult and dangerous, but it is also difficult to automate work at such type sites. One reason is that construction sometimes calls for movement across a “Free Frame” – a structure built to keep a slope from collapsing – and because of the ups and downs of the natural slope, it is difficult to design a purposeful simple mechanism to move on this frame. We propose a sensor-based quadruped walking robot that moves on the slope without damage to the surface of the frame, and developed a TITAN VII prototype robot. We detail the techniques required by this type robot to move and work on steep slopes. Practical ways of A) detecting positions and orientations of frame surfaces on rough slopes and B) stepping over the frame and maintaining the stability of the robot using positioning, are presented and their effectiveness is verified through experiments.