This research reveals that the static resistance of trees varies according to whether trees depend on soil water conditions in the case of Japanese larch, whether they originated in seeding or transplanting in the case of Japanese oak, and whether they grow close together or not in the case of Japanese larch. This is verified by experiments of pulling down trees that grow in different conditions. It has been said that forests play important roles in preventing sediment disasters. However, it has been unknown to what extent which kinds of trees contribute to preventing debris flow in mountain areas. Therefore, we compared differences of the maximum tree-pulling moment of several kinds of trees that have different soil water conditions, different origins in growing, and different grove density by conducting experiments of pulling down the trees. In the experiments, we calculated the maximum tree-pulling moment whenever a heavy machine or TIR FOR pulled down a tree by drawing a wire passed around the tree at a height of one meter. The experiments show three results. First, there are no differences of the maximum tree-pulling moment even among trees that depend even on different soil water conditions. Second, the maximum tree-pulling moment of trees originated in seeding is the same as for those in transplanted. Finally, there are negative correlations between the maximum tree-pulling moment and the grove density