The purpose of this study was to examine the effects of a low-frequency, extremely short-term exercise intervention on the improvement of the physical fitness of middle-aged and elderly persons. The subjects were eight middle-aged and elderly persons who participated to an extension course of Hiroshima Bunka Gakuen University “The course of Sports and Health for middle-aged and elderly persons 2016”. We conducted an exercise intervention once a week for the subjects over the course of one month（ 5 times）, and measured their physical fitness（ by the New Physical Fitness Test of Japanese Ministry of Education, Culture, Sports, Science and Technology） before and after the intervention. As a result, the total physical fitness score showed a significant increase（ p<.05） after the exercise intervention. Three of the physical fitness tests,including standing on one leg with eyes open, seated toe touch, and 10 m walking obstaclecourse, showed significant increases （p<.05 in any of the categories）. It is concluded that to improve the physical fitness of middle-aged and elderly persons contributes to extension of healthy life expectancy and improvement of mortality, even if it was a low-frequency, extremely short-term exercise intervention.