As one of the oldest Islamic societal organizations, Muhammadiyah is involved in the constitution formation process. This paper aims to analyze Muhammadiyah’s contribution to the state constitution from the start of the independence up to the amendment in the Reformation Era. Results showed that with its mostly Muslim population, the Islamic nomocracy idea that was developed in the dialectics of the Islamic societal organization largely influence Indonesia’s constitutional formation and legal construction Pancasila. The Islamic nomocracy idea offered by Muhammadiyah dynamically developed in line with the social, political, and religious dynamics in Indonesia from the independence up to the Reformation era. In that conception, the state of Pancasila is a final form of the co-existential relationship between religion and the state.