Soil behavior generated by a root-cutting blade moving under the ground of an automatic spinach harvester for spinach for eating raw is analyzed in this paper. It is difficult to harvest spinach for eating raw by using automatic harvester because stems and leaves of spinach are soft and easily bruised. Thus the harvester which can be widely used among farmers has not been developed. To overcome the difficulty, we have been developing the automatic spinach harvester which does not bruise spinach. A trajectory of a root-cutting blade is very important to achieve this automatic harvesting without bruising spinach because the motion of cutting the root of spinach is influenced by soil which the blade presses and moves in. In this paper, accordingly, some characteristics in the behavior of soil caused by the moving blade are clarified by using the distinct element method (DEM) to investigate the automatic harvesting. In conclusion two important characteristics, the velocity of the moving blade and the volume of soil in the passage field the blade moved, are pointed out and described.