Although the number of unwed mothers have mental health problems and intellectual disability, little research have focused on their mental and cognitive status. Since there has been public stigma of unwed mother in South Korea, they tend to conceal their status and less likely to seek psychiatric and psychological help. In this context, this study aims to assess current status of their mental health and intellectual characteristics. A total 48 unwed mothers from two shelter homes in South Korea were agreed to participate in the study. To compare mental health and intellectual abilities of unwed mothers with the general women population, reference data from national studies was used. Unwed mothers were more likely to have mood disorder, post traumatic stress disorder(PTSD), alcohol and nicotine use disorder, attention-deficit hyperactivity disorder (ADHD) than the general women population. Among 48 participants, 20 (41.7%) were lower than 70 Intelligence Quotient (IQ) and the mean of IQ (78.31) was significantly lower than normalized IQ mean of general women population. In logistic regression analysis, psychiatric disorders were associated intellectual disability. This study confirmed that unwed mothers dwelling in Korean shelter homes have more experience of mental disorders and lower intellectual ability than general women population.