This study clarified the actual situation of physical soil erosion due to the passage of Cervus nippon (hereafter, deer) in the forest edge and the factors that affect it. The study area was the forest edge of a Japanese cypress forest and a larch forest bordering a residential road on the west side of the Mochizuki Highland Ranch in Mochizuki-machi, Saku City, Nagano Prefecture. Soil erosion surveys were conducted at multiple locations, measuring the vertical exposure height (unit: cm) and direction of exposed roots from the ground surface. The results showed that there were clear signs of erosion in a perpendicular direction caused by the passage of deer at the forest edge. The average and standard deviation of the exposed height were both higher in the larch forest than in the cypress forest. Furthermore, the polar coordinate distribution of the exposed height showed that the root systems were exposed more in the direction of the steepest slope, but there were also some cases where they were exposed in other directions. As the average and maximum exposed heights increased as the slope angle became steeper, it was thought that in the forest edge slope, in addition to the normal sediment erosion, there was a possibility that the sediment erosion would be added due to the trampling of the deer when they passed through.