Syrian conflict started on January 26th, 2011. At first, the conflict in Syria was an internal conflict between the government of Bashar Al Assad and the Rebel, the descent into war began with the violent and brutal repression of peaceful pro-reform protests, which later turned into an armed uprising against the regime of Bashar al-Assad, and has since become a regional conflict involving state and non-state actors. In the development of the conflict there were some parties which intervened to provide support for the Bashar al-Assad. One of the countries that intervene against Syria is Russia. In the armed conflict which happened in Syria on September 2015 and early October 2016, more than 9,000 people including 4,000 Syrian civilians were killed by the Russian airstrikes. The International Humanitarian Law hostilities regulate the protection of victims of conflict and also restrictions on the means and methods of warfare. The methods of this research is normative legal research. By using a descriptive qualitative method, the research aims to know what is the causing factor of the conflict in Syria and how the International Humanitarian Law regulates the responsibility of the State and Individual. The result of this research shows that Syria is not a state party in several international conventions namely Additional protocol II/1977 and United Nations Convention on the Law of the Sea 1982 (UNCLOS 1982). Therefore, these conventions are not applicable formally in the armed conflict in Syria. Then, based on Customary Humanitarian Law, Syria and Russia are responsible for the untargetting attack that occurred in Syria and they are required to make full reparation for the loss or injury caused by untargeting attack. Furthermore, Individuals belonging to an Organizations or State are held personally responsible before the law. Then, the United Nations Security Council (UNSC) must carry out the mandate of UN Charter Articles 41 and 42 and UNSC as the main organ which responsible for the maintenance of international peace and security.