Marriage is a basic human need, the continuity of the marriage is also influenced by property in marriage. There is premarital agreement in the marriage law, that is used to deviate from the concept of mutual property in marriage. Indonesia still uses the Civil Code as a legal source in addition to Law No. 1/ 1974 and The Constitutional Court’s Decision Number: 69 /PUU-XIII/2015 to regulate premarital agreement. In purpose to fill the legal vacuum in agreements and materials law, premarital agreement is still referred to BW (Civil Code), the heritage of the Netherlands secular state, which is different from Indonesia as a legal country based on Pancasila. Secularism separates religion from its laws and regulations while Pancasila contains the Belief in the one and only God as the first principle that is manifested through religion and belief. This is a positive- normative legal research, with a qualitative research form. It uses secondary data from library searches, complemented by the results of interviews with selected sources. The collected data will be analyzed by deductive methods. As the result of this research, we know that the fundamental difference in the meaning and purpose of marriage between the Law No. 1/ 1974 and the Civil Code is that the premarital agreement cannot be separated from marriage law, even though it is also a part of agreement law. So, it is necessary to improve policies related to property agreements in marriage to avoid clashing norms.