Rovers are the most important devices for planetary exploration. Rovers are required to traverse many situation of ground, on various form's stones, loose soil, steep slope etc. There are some technologies that large obstacles such as stones can be avoided by using cameras or lasers. However, it is extremely difficult for rovers to traverse loose soil, especially "loose soil with steep slope". If the area being traversed is sloped, these rovers might not work. During a lunar exploration mission, rovers must be able to traverse slopes. Lunar surfaces are mainly characterized by loose soil called regolith, and the ground is very steep. We developed a newel rover to adapt such condition. Proposed rover has an ability to traverse loose soil with steep slope. It is to use the shearing strength of soil. This means that we use characteristic of soil that the shearing strength of deeply soil areas was very strong compared with surface of ground. If the rovers can make use of the deep area of loose soil, they may be able to support their weight on slopes with loose soil. Therefore, we employ piles to penetrate into the deep area of loose soil. In here, we have to determine the optimal piles to adapt the supporting force and the penetration resistance. We measure the supporting force and penetration resistance force to evaluate the pile's effect quantify. Moreover, we simulate the supporting force using theory of Broms. Finally, we select the optimal piles.