The research of this article is motivated by the formulation in the Marriage Law No. 1 of 1974 where there are several articles that regulate the inheritance rights of illegitimate child, namely article 42 and article 43 that are not just as there is no attainment of justice in the inheritance rights of illegitimate child so that the child has not received welfare in his life therefore it need to be reconstructed to achieve justice. This research is a non doctrinal/ socio legal research which is descriptive analysis. With the constructivism paradigm. This research approach method is empirical, supported with normative and comparative approach. Primary data sources are interviews, observations, while secondary data sources are primary, secondary and tertiary legal materials which are then collected and analyzed using data triangulation. The result shows that the inheritance rights of illegitimate child is not yet fair because there is no attainment of justice in the inheritance rights of illegitimate child so that the child has not received welfare in his life, therefore, a reconstruction Inheritance rights of children outside of marriage based on the value of justice is needed by adding another paragraph in Article 43, that states that the civil position in the law gave no distinction between children outside of marriage and within marriage or gave one side a prioritize over other.