A leg-wheel robot, Chariot II, has been developed for the purpose of moving on an unknown unexplored rough terrain without using many sensors such as visual and tactile/force sensors that need accurate and complex control and heavy calculations. The robot equips with mechanically separated wheels and legs, which allows to utilize the advantages of two mechanisms. This paper presents a set up method for legs' compliance of the leg-wheel robot to decrease the pitching and rolling movement of its body when moving on unknown unexplored rough terrains. Using the proposed method, the leg's basic compliance is adjusted in proportion to the roughness of the surface when a phase of leg changes from returning phase to supporting phase. The effectiveness of this method is confirmed by simulation and experiments.