We introduce the stable walking system for the large 6 legged walking machine. The machine was developed to realize a solid and reliable walking vehicle for practical uses in forestry steep terrain with spread mechanical elements those are used in usual construction machines. It weighs about 4,000[kg] including the working machine. Owing to a mounted diesel engine and hydraulic drive system, it can walk around on the soft soil terrain and climb the steep slope of inclination up to about 30 degrees, and walk along contour line of lateral inclination up to about 41 degrees. Finally it walked well, despite it was tested on severe steep terrain where a lot of shrubs and stumps exist. We tested and evaluated the machine mainly about its significant walking method, hydraulic motion control system for walking and real-time inclination correcting system.