Hepatitis B virus （HBV） belongs to the family of Hepadnaviridae and infects more than 2 billion people over the world. Children less than 5 years of age who become infected with the HBV are the most likely to develop chronic infection and eventually proceeds to liver cancer, which accounts for 33% cancer deaths. Prevention of HBV transmission is essential to reduce the risk of liver cancer. In order to reduce HBV transmission, it is necessary to apply a comprehensive prevention system to block vertical and horizontal transmission. Vertical transmission of HBV from mother to child is the most frequent cause in the developing countries. The HBV status of HBsAg, HBeAg, and HBV DNA in all pregnant women is screened to prevent transmission from the prenatal stage. Antiviral therapy should be considered, if HBV DNA exceeds 5 log10 copies/ ml. Horizontal transmission in the postnatal period can be prevented by universal HBV vaccination. However, if the HBeAg status of the mother becomes positive during the pregnancy, additional treatment of hepatitis B immunoglobulin, HBIG is required. Unfortunately, in most countries, comprehensive prevention systems that block vertical and horizontal transmission are not applied due to cost issues and inconvenience of transportation for residents. The vaccination program has not been appropriately established in all countries, even though the universal HBV vaccination has been widely introduced. Because of such circumstances, the rate of HBV transmission is still at high level.