This study was to investigate the prevalence and the affecting factors of cognitive function and depression among the elderly in an island community. The sample was collected from 116 elders who have 65 or more age. Subjects were tested for cognitive function with MMSE-K(Mini Mental State Examination- Korea) and depression with Yesavage' GDS(Geriatric Depression Scale). The main results were summarized as follows. 1. The prevalence rates of severe cognitive impairment were 19% and rate of mildly impaired was 18.1%. The mean score of depression was 5.39. 2. The variables such as sex, age, educational level, marital status had the significant differences with cognitive function impairment. The correlation between cognition level and ADL/IADL, sleep pattern showed statistical significance. 3. marital status had the significant differences with depression. The correlation between depression and ADL/IADL, physical disease showed statistical significance. 4. The correlation between cognitive function level and depression score showed negative significant relationship (r=-.258). 5. In the multiple stepwise regression, ADL/IADL age and sex were selected as highly correlated variables of cognitive function and the R² value for these variables was 48.1%. ADL/IADL and physical disease were selected as correlated variables of depression and the R² value for these variables was 11.3%. In conclusion, main variable which had close relation to the cognitive function and depression was ADL/IADL.