In the present study, the author selected Kendo among many sports because of the lack of information on the health administration of the Kendo athlete, in spite of the increase in this sport. The present study is specifically concerned with the changes in the excretion of urinary protein as an index of physical exertion during and after Kendo exercise. (1) The longer the duration of exercise was, the more urinary protein that was excreted. The increase was logarithmic against the duration. (2) When the total exercise duration in a day was from 1 to 2 hours, the excretion of urinary protein increased logarithmically, but from 2 to 3 hours it did not change significantly. Over 5 hours it increased again remarkably. (3) In the recovery process after Kendo excercise for 2 hours, an excess amount of urinary protein excretion was observed within 0-30 minutes after stopping excercise. After 30-60 minutes although the tendency of recovery was observed, the individual variation was high in this period. After 150 minutes, the urinary protein excretion of all specimens returned to the level which was observed before the excercise. (4) In conclusion, the excretion rate of urinary protein per unit time seemed to be a more suitable index of the severity of the exercise and the restoration from exertion of Kendo athlete than the level of urinary protein easily affected by condensation of excreted urine.