The purpose of this study was to examine the sensitivity of the Japan Fitness Test for elderly people to assess the effects of aging. The participants were 250 male and 377 female, (627 in total) elderly people in residential care. The Japan Fitness Test consists of 6 test items (Gripstrength, Sit-ups, Sit-and-reach, Single-leg balance with eyes open, 10 m hurdle walk, and 6-min walk). Two-way multivariate analysis of variance (MANOVA), and analysis of variance (ANOVA) were used to determine effects of gender and aging on test performance. To estimate the sensitivity of each test for assessing aging, effect sizes (ES) of between young-old (aged 65-74 years) and old-old (aged over 75 years) were calculated. The criterion of the sensitivity of each test was more than ES=0.50. MANOVA and ANOVA results revealed significant effects for age groups on all test items, and there were no significant interaction for all test items except Sit-ups. ES of Grip strength, Single-leg balance with eyes open, 10 m hurdle walk, 6-min walk were indicated more than ES=0.50. For Sit-ups, while ES was 0.71 in male, it was low value (ES=0.25) in female. From these results, it is concluded that the Japan Fitness Test items are sensitive to assess aging effects with the exception of Sit-up routines performed by elderly women in female.