Smoking is harmful to the health of adolescents because their bodies are still growing. The aim of this study was to analyze the association between the smoking status of Korean adolescents’ parents and friends and their own smoking behavior. The study assessed a nationwide sample of 72,060 middle and high students from the 10th Korea Youth Risk Behavior Web-based Survey (2014). Descriptive analysis, chi-square tests, and multiple logistic regression analysis were used to probe the association between family and friend smoking status and adolescent smoking behavior. The current cigarette smoking rates were 13.3% of boys and 4.1% of girls. The corresponding rates for electronic cigarette smoking were 4.1% and 1.5%, respectively. Higher exposure to secondhand smoke, smoking by any family member, more friends smoking, and witnessed smoking at school were associated with current smoking and electronic smoking. The smoking status of family and friends was significantly related to adolescent smoking behavior. These results should be considered in designing programs to control adolescent smoking.