Recently, aquatic exercise has been more widely performed as it reduces the eŠects of weightbearing on the lower extremities and leg joints. Moreover, decrease in trunk muscle strength is an important factor in chronic low-back pain in obese women. The purposes of this study were to evaluate the eŠects of aquatic exercise training using new water-resistance equipment on abdominal circumference measurements, trunk muscles strength, and ADL (Activity of Daily Living) in older women. Subjects were divided into a resistance training group (those using the equipment) and a non-resistance training group (those without the equipment). The aquatic exercise training mostly consisted of abdominal muscle activity. All subjects underwent physical testing. In the resistance training group, abdominal circumference, abdominal muscle strength, and ADL measurement were signiˆcantly improved. Additionally, a low negative correlation was found between the degree of change in abdominal circumference and ADL scores. As it became easier to maintain posture, stand, and move, activities in everyday life improved with the increase in strength of the lower extremities and trunk muscles. These results demonstrated improvements in abdominal and back muscle endurance and suggested that, as abdominal circumference decreased, ADL improved. This aquatic exercise training using the new water-resistance equipment may be used by the elderly to improve abdominal and back muscle endurance.