Recently pregnant women take more drugs than before due to the trend of increasing maternal age. Though most drugs are safe, a small percentage of them may have unintended adverse consequences for either mother or child. So any unnecessary drug should not be given to pregnant women; however, when necessary, some medications cannot be withheld. Counseling for drugs during pregnancy is one of most important and difficult tasks of obstetricians. Most drugs are classified FDA category C, and there are many new drugs that have not been categorized yet. In addition, many drugs in category X are not absolutely contraindicated during pregnancy, and several drugs in category C or D are clear human teratogens. In this article, the author introduces drugs that we can use for common illnesses during pregnancy available in Korea.