Before the contract is one of the conditions on which jurists have disagreed. Famous jurists do not consider these conditions to be mandatory. On the other hand, many jurists believe in the legitimacy of this condition. In addition to the theoretical jurisprudential reasons for the invalidity of the construction condition, they cite other jurisprudential reasons to prove their theory, which of course are not without problems. Therefore, in jurisprudential texts, we do not find a definitive theory on the validity or invalidity of the construction condition. Iranian law, based on Article 1128 of the Civil Code, considers the above conditions to be mandatory. The most important legal reason for proving the necessity of the construction condition is the clarification of the validity of the construction condition in marriage and its extension to other contracts. The jurists have explicitly accepted the construction condition in marriage. According to jurists, when a foundation condition in marriage is valid despite its existing sensitivities, it should undoubtedly be binding in other aspects of contracts as well.In this article, we will first outline the jurisprudential texts of the theory of the validity of the construction condition and cite their evidence and critique, and then we will discuss the legal arguments for this theory and critique some of them, and we will try to prove this theory. Finally, we will refer to the jurisprudential document of the above article