Human trafficking is a modern form of slavery, occurring both nationally and internationally. With the development of information technology, communication and transformation then the mode of human trade increasingly sophisticated. Human trafficking becomes one of the five greatest crimes in the world to be overcome because of the effects not only on the economic, but also on the political, cultural and humanitarian aspects. It is therefore necessary to review the forms of human trafficking, its causal factors and legal instruments that can be used to combat trafficking. Answering these problems then this research is done by normative legal research methods. The results of research show that the forms of people's engagement include sexual exploitation, force labor, domestic slavery, illegal adoption of illegitimate children, debt bondage, mail order brides, and human organs trade. The results also show that poverty, population movement, discrimination and patriarchal culture are the factors causing human trafficking. Give the dangerous nature of trafficking in persons, the state or government of Indonesia should be responsible for preventing and overcoming human trafficking with existing legal instruments.