Objective: The study was conducted to identify the effects on blood pressure, stress and flexibility after applying the four-week Ai Chi exercise to 12 women aged 65 or older.\nMethod: In this study, a total of 12 people were selected for final analysis, excluding two persons who participated in the program but who did not participate in the program. The researchers conducted an underwater exercise three days a week for four weeks and measured blood pressure using the OMRON HEM-1000. Before the test, the average value was used after 4 weeks. The flexibility, set and repair test was measured by a digital pole system (T.K.K. 5412).\nThe stress measurement analyzed the saliva cortisol as Enzyme-linked emunoassay (EIA).\nResult: Changes in blood pressure were found to have no statistical significance in both systolic and relaxation blood pressure prior to underwater exercise (p>.05). After the Ai Chi underwater movement, the flexibility of the body was significantly changed in the measurement results. This was statistically significant (p<.05). Ai Chi It has been found to be effective in reducing stress due to reduction of the concentration of saliva cortisol (p<.05).\nConclusion: This study shows that the Ai Chi underwater movement is effective in increasing flexibility and reducing stress in women s older adults. Therefore, based on the results of this study, I believe that the Ai Chi, an underwater movement that is not yet well known as an effective method of mediation for the elderly but for the general public who are limited in scope or have health problems due to muscle strength and balance.