In falling accidents in the elderly, there might be a delay in reaction time or movement time in lower extremity. The purpose of this study was to measurement of three axis acceleration during step descending. The subjects were 10 healthy young men. We measured three axis acceleration during step descending with the eyes open and closed. As a result of measurement, the acceleration during step descending greater than the acceleration during walking. There was no significant difference in during walking that the acceleration with eyes open and closed. However, during step descending that the acceleration with eyes closed greater than the acceleration with eyes closed. The results suggest the possibility that three axis acceleration reflects the balance.