Purpose: The purpose of this study was to investigate the effects of health-related characteristics, social support, and depression on the cognitive function of elders who live in areas served by community health posts. Methods: The participants were 277 elders selected from M county by convenience sampling. The data were collected from May 20 to July 10, 2009, and analyzed using frequencies, t-test, ANOVA, Duncan test, Pearson correlation coefficients, and stepwise multiple regression with SPSS/WIN 17.0. Results: The mean score for cognitive function of the participants was 18.8. Both cognitive function and health-related characteristics showed significant differences according to perceived health status. Cognitive function had a significantly negative correlation with depression. Depression had a significantly negative correlation with social support. Cognitive function had a significantly positive correlation with social support. The factors influencing cognitive function of elders were perceived health status, social support, and depression. Conclusions: The results of this study suggest that programs be developed to increase perceived health status, social support and to decrease depression for elderly people.