Surfaces of exploration targets for lunar/planetary robots (rovers), such as the Moon and Mars, are covered with fine sand. This sand makes the wheels of a rover susceptible to slip, and in the worst case, can lead to immobility. To avoid such situations, it is important to analyze the mechanics of the interaction between the soil and wheel. Hence, various devices to measure the normal stress distribution beneath wheels have been proposed. However, most of the conventional equipment is only able to measure the distribution in a flat soil environment. In practice, when a rover traverses sandy slopes, the normal stress distribution is not expected to have a simple shape like that for a flat environment. Therefore, we propose a measurement device for the two-dimensional normal stress distribution of a wheel on a lateral loose soil slope. Some experimental results prove the validity of the method.