It is difficult for Elderly persons to arise from chair because of muscle deterioration. This paper proposes that elderly persons' arising action and its support tool. The point of adequate arising action is making the upper body lean forward and pulling legs. As a result, the body's center of gravity move into basal surface, and the elderly persons can use leg and arm force effectively. To realize those actions, we developed a cushion type support tool that can change seating angle freely. When using the support tool, the values of acceleration, arm force and arising time were improved. Additionally, antiversion angle and peg position became appropriate. As a result, the proposed arising action and the support tool are effective in improving elderly persons' arising action.