The Nyentana Nyelidihi marriage system in Balinese customary law society is a solution to preserve family lineage without any sons, but this system often places men in a legally and socially vulnerable position. This study analyzes the forms of legal protection that can be given to men in this system, especially through prenuptial agreements that regulate inheritance rights, asset distribution, and social status. An empirical approach is used to explore the practice of Nyentana Nyelidihi in Bali, especially in Tabanan Regency, with interviews and observations as the main methods. The findings show that the integration of customary law and modern law can create a better protection mechanism, providing guarantees of justice for men while maintaining Balinese customary values. This study emphasizes the importance of public awareness and government support in strengthening regulations that support gender equality and legal certainty in customary marriage.