Objective: This study aimed, first, to develop core strength training equipment with elderly-friendly, easyto-use features and, second, to investigate the effect of core strength training using the equipment on theperformance and stability of the elderly in activities of daily living.Method: In this study, we developed training equipment with a stability ball that can be used for performingcore strength exercises in the elderly. Twenty-three elderly subjects (age: 77.87 ± 6.95 years, height: 149.78± 6.95 cm, and weight: 60.57 ± 7.21 kg) participated in this study. The subjects performed the core strengthtraining exercise with 16 repetitions for 8 weeks (2 repetitions per week). Performance in activities of dailyliving was assessed by using the Short Physical Performance Battery (SPPB), a test of going up and down4 stairs, and one-leg static balance test. Stability was quantified as changes in the center of pressure (COP)and C90 area.Results: With the core strength equipment, trunk core strength exercise could be performed by pulling orpushing a rope with 2 hands on the stability ball. During the task, the tension in the rope was manipulatedby a motor connected to the rope and the COP of the subject was measured by 4 load cells mounted in theequipment. Our results showed that the SPPB score was significantly higher (p < .05), the time to completethe "going up and down 4 stairs" test was significantly shorter (p < .05), and one-leg static balance statisticallyimproved under an eyes-open condition (p < .05) after as compared with before the core strength training.The changes in the COP in the anteroposterior and mediolateral directions, and C90 area were significantlylower in the posttest (p <. 05) than in the pretest.Conclusion: The core strength training exercise using the equipment developed in the present studyimproved the performance and stability of the elderly in activities of daily living.