The purpose of this study was to investigate the adaptability of equilibrium function in the old. The subjects were 39 university students (young group) from 18 to 21 years old and 48 old age persons (old group) from 62 to 78 years old. A vibration table with a force plate on which the subjects maintained the standing posture with eyes closed, was vibrated sinusoidaly in anteroposterior direction under the condition of 2.5 cm amplitude and 0.5 Hz frequency.The trial time on the vibration table was one minute. This trial was repeated 5 times with inserting a rest sitting on a chair for one minute. The equilibrium function of standing posture was evaluated by the mean speed of the fluctuation foot pressure center.
　The mean speed was corrected by the height. The results were follows :
　1) The equilibrium of the old group was significantly inferior to that of the young group in all trials.
　2) In all subjects of the young group, the equilibrium function improved with repeating the trial. In the old group, the subjects of about 15% didn't show the improvement of equilibrium function with repeating the trial, on the other hand, a few subject showed the improvement similar to the young group. Conceivably, the ad-aptability of the old group was inferior to that of the young group.
　3) In the young group, the sexial difference of equilibrium func-tion wasn't recongnized in all trials. In the old group, the equilibrium function of male was superior to that of female untill the third trial, and after that trial a significant sexual difference wasn't shown. It was conceivable that no sexual difference of the adaptability of equilibrium function exist.

DESCENTE SPORTS SCIENCE Vol.13/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE