Abstract: The present study aimed to determine the mediating effect of social relationship on the effects of Basic and Instrumental Activities of Daily Living (BADL and IADL) on the depression of elderly women with chronic diseases. Of the raw data of the 2014 National Survey of the Living Conditions and Welfare Needs of Older Koreans which was conducted on a national sample, the data of 5,633 elderly women aged 65 years or older with one or more chronic diseases diagnosed by a doctor were analyzed. Data were analyzed using t-test, ANOVA, Pearson correlation, Hierarchical regression analysis and Sobel’s test. The results showed that BADL and IADL were positively correlated with depression and negatively correlated with social relationship whereas depression was negatively correlated with social relationship. The findings also showed a partial mediating effect of social relationship on the effect of BADL and IADL on depression. These results indicate that social relationship can act as a protective factor that contribute to reducing the depression of elderly women with chronic diseases that may be caused by their decreased daily life competence.