Pancasila is the unity and unity of the Indonesian nation with the function of being the basis for carrying out government administration and regulating the state structure as a whole. Pancasila is a national symbol that functions as the basis for carrying out government administration and regulating people's daily lives. The Pancasila ideology helps shape the character of a nation that is honest, disciplined, thinks critically, is responsible, is fair, loves the country, is tolerant, embraces each other and has high social awareness. Constitutional Court decisions that reflect constitutional values ensure a reexamination of the 1945 constitution and often lead to conflicting situations such as disagreements over election results that must be resolved by all parties involved. The Constitution has the responsibility to make the first and final decisions regarding changes to laws relating to the 1945 Constitution. The aim of this research is to determine the role of the Pancasila Ideology in the Development of the Constitution and Legal System in Indonesia. This research uses the literature review method, which is research carried out by collecting library data, or research through various sources of information. The results and discussion in this research Pancasila is an ideology or guideline for Indonesian society and the laws that apply in Indonesia must be based on the 1945 Constitution. The Constitution is the foundation of the government and its implementation requires a thorough understanding of the social background and long-term goals of a country. Therefore, the philosophical basis of the constitution must be clear and consistent with the wishes of the government, which basically reflects the wishes of the people. It can be concluded that Pancasila contains values that can be implemented by the Indonesian people. In Pancasila there are the values of norms, ethics and moral behavior. Meanwhile, the 1945 Constitution contains a legal basis in written form. The laws that apply in Indonesia must be in accordance with the 1945 Constitution. The law has a high position, therefore every Indonesian citizen must comply with all applicable laws and will receive sanctions if Indonesian citizens commit deviations.