To develop a mechanism that will support the standup motions of elderly people, a control method and operation-start condition are proposed using a measurement apparatus. On the basis of those results, a support mechanism is then designed with a practical size and experiments are conducted to verify its effectiveness. In younger subjects, the floor's reaction force decreases when the support mechanism is used, which is the same effect gained when the measurement apparatus is used. However, similar effectiveness is not seen in elderly subjects because of the different way in which they hold the handrail. Thus, in the future, the mechanism's design will be revised, taking into consideration the elderly's specific characteristics.