This study examined the association between marital status and mental health(depression, and suicidal ideation) of Korean adults by age and sex, using 2005 Korean National Health and Nutrition Examination Survey data. Differences of marital status in depression and suicidal ideation were assessed by age and sex-specific prevalence according to each stage of the life course. Our results indicated that adults who divorced, separated, and widowed had significantly higher risk of poor mental health than married adults. Men with no spouse at the stage of middle and older aged are reported higher in depressive symptom than married men. For the suicidal ideation, men with no spouse had higher risk of suicidal ideation through all stage of life course. Women were more likely to report depressive symptom and suicidal ideation than men through all stage of life course. But we could not found the mental health advantage of marriage among Korean women through all stage of life course. Based on findings, the study clearly indicate that the implication of marriage on mental health could be different for adults of different age group and sex.