Folic acid supplementation before pregnancy is known to significantly reduce the risk of having a baby with neural tube defects (NTDs). Therefore, it is important for women to be aware of the effects of folic acid supplementation before pregnancy. The purpose of this study was to investigate the awareness and preconceptional use of folic acid and to assess the current knowledge about folic acid among low-income pregnant women in Korea. A questionnaire survey was conducted in 2012. Five hundred pregnant women were selected from the waiting list for the Nutriplus program implemented in public health centers using a multistage clustered probability sampling design. Data from 439 women were analyzed after excluding ones with incomplete answers. Among women who responded to the questionnaire, 65.6% had heard of folic acid before pregnancy, and 26.4% reported on the preconceptional use of folic acid. Women with a university degree or higher education were more likely to be aware of folic acid and to take folic acid in the preconception period. In a multivariate logistic regression, when age, education level, household income, employment status, gravidity, parity, and folic acid awareness were included in the model, folic acid awareness was a strong predictor of preconceptional folic acid use. As of interview, 85.4% and 77.7% of women were aware of the NTD-preventive role of folic acid and the appropriate time to take folic acid, respectively. The main sources of information on folic acid were healthcare professionals (41.2%), friends and family members (31.2%), and the media (26.5%). Our results suggest that public health strategies are needed to increase the preconceptional use of folic acid among Korean women.