Objectives: This study is conducted to identify the effects of the activity program for preventing dementia against depression, cognitive function, and quality of life for the elderly. Methods: A non-equivalent control group with pretest-posttest design was used on 50 elderly who were assigned to the experimental and control group (25 for each group). Results: Cognitive function was significantly different between the two groups of the pretest and posttest (Z=4.217, p<.001). There were significant differences between the two groups of the pretest and posttest (Z=-2.324, p=.020) for the quality of life on the EQ-5D index. Conclusions: These findings confirmed that the activity program for preventing dementia was effective for improving cognitive functions and quality of life for the elderly. Therefore, it is further encouraged to perform the activity programs for preventing dementia within other community health posts and community centers. It is necessary to study the emotional supports from community health posts in the future.