Purpose: This study aims to identify factors of life satisfaction of the adults with developmental disabilities, focusing on the comparison between young adult and middle old-aged. Method: This study used the 2016, 2017, and 2018 data of the Panel Survey of Employment for the Disabled(PSED). Results: Among the old adults with developmental disabilities, the life satisfaction is significantly related to subjective economic position, subjective health status, leisure activity, social discrimination due to the disability. For the young adults with developmental disabilities, the life satisfaction is significantly related to subjective economic position, employment status, subjective health status, participation in everyday activities, social discrimination due to the disability. Conclusion: On the basis of the results, some suggestions on the policy and practice of the social services for disabled olders with developmental disabilities were presented. This study will contribute to the exploration of the strategies for improving the life satisfaction of elderly people with developmental disability.