Observance of justice in polygamy is one of the most important moral propositions in the family. In the Holy Qur'an, polygamy is permissible; however, with modification, it is limited to a maximum of four permanent women. Also, the Qur'an has ensured that equality between wives is a prerequisite for polygamy. The purpose of this article is to explain justice in polygamy. The research method is analytical-descriptive and documentary. In this article, based on verses relating to polygamy, the concept of family justice in terms of the Qur'an and traditions has been studied. The findings of this research indicate that swearing and alimony are the most important aspects of justice in the traditions of the infallibles (pbuh), and that inner justice, in which justice is in the love of the heart, and is unnecessary and beyond the will of man, is not included in the terms of justice in polygamy. Therefore, Islam did not oblige polygamy to anyone, but, given the nature of individuals, and on the expediency of the human community, allowed polygamy to be limited to righteousness in order to eliminate all wrongdoings in this regard.