In 1958, Indonesia ratified the 1949 Geneva Convention into Law Number 59 of the Republic of Indonesia. By the Geneva Treaty of 1949, known as International Humanitarian Law, Indonesia's acceptance of the Convention provides it with international rights and duties. Certain and serious offences, including genocide, a war crime, and aggressive crime, are specifically included in International Humanitarian Law as essential components. Article 28 of the Second Amendment to the 1945 Constitution, TAP MPR XVII of 1998 about Human Rights, Law Number 39 of 1999 about Human Rights, and Law Number 26 of 39 of 1999 about Human Rights are used by Indonesia to anticipate the severe crime as the implementation and enactment of International Humanitarian Law. International Humanitarian Law and the means for its application have not been fully included in the law. This is because war and aggression are two significant crimes for Indonesia has no provisions. International and national processes may be utilised to execute international humanitarian law. As a result of Indonesia's failure to ratify the Rome Statute of 1998, the international process for enacting international humanitarian Law has not been properly defined since Indonesia has not signed. This study examines the implementation of International Humanitarian Law in a state's national mechanism and the Indonesian national law's compliance with IHL.