Planetary exploration robots are required to explore rough and steep areas such as craters and cliffs to achieve scientific goals. Most of the proposed rovers have some wheels to move on a planetary surface. However, it is difficult to traverse on a rough terrain flexibly. A legged rover can provide higher capability of moving in such a rough terrain than wheeled robots. Therefore the authors have studied a small and lightweight rover which can move across a rough terrain such as a steep slope inside craters. This paper deals with design scheme for a light walking rover for planetary exploration. This paper presents analysis on the proposed weight arrangement scheme to reduce the weight of the walking robots. The effectiveness of the proposed scheme is shown by computer simulation and hardware study.