The righting reflex to avoid falls is altered with advancing age. The purpose of the present study is to find a good index for representing how the righting reflex is exacerbated with advancing age. We carried out stabilometry for standing subjects who were healthy adults with age <51 (9M & 11F, younger group) and ≥51 (22M & 8F, elderly group). The stabilometry required the subjects to stand on a stabilometer with fixing their eyes to the screen (1 min) and their eyes closed (the following 1 min). Statokinesigrams resulting from the stabilometry were analyzed by 8 indices. In the "Eyes opened" state, significant changes in previous indices were not found by a decline in the equilibrial function with advancing age. Our proposed index, a total of local sums of forces on chains I, was regarded as the most robust and appropriate index to statokinesigrams for the "Eyes opened/closed" state. This index was applied to the simulation of the elderly (pseudo-elderly study); the subjects were healthy adults with age of 19-29 (5M & 19F) and wore apparatuses as glasses, earplugs, and weights in the stabilometry. These indices obtained from the statokinesigrams indicated that pseudo-elderly group was the most stable, and the elderly group was the least.