This paper reports an analytic result of elderly person's standing up action using a support tool. As the results of advanced research, followings were necessary for elderly persons to realize a smooth standing up action; making the upper body lean forward, and pulling legs to the chair's legs. To act those points, we developed a support tool, cushion type support tool with movable flange. As a result of applying the support too to elderly persons, they could stand up smoother than the cases that they didn't use the support tool. Those values related standing up action, such as maximum acceleration, maximum arm force, arising time, antiversion angel, and feet position, were improved. Furthermore, elderly persons felt making stand up easy. We could confirm the effectiveness of the support tool.