An agreement made before a notary has strong legal force as an authentic deed. However, in other cases, there is a hidden agreement that is not revealed in front of the notary regarding the land purchase and sale agreement that uses the name loan. This condition creates a legal dilemma because an agreement that seems legitimate and authentic in the eyes of the law, in fact, contains elements of dishonesty or concealment of facts that can affect the validity of the agreement. This raises fundamental questions about legal certainty and how the law should handle these kinds of practices, the author tries to identify the problem based on the above background, first, how is the legal certainty of the land sale and purchase agreement carried out through name borrowing? Second, what is the responsibility of the notary if he knows the application for making a land sale and purchase agreement made through a name loan? The research method used in this thesis research is to use a normative juridical research type with a problem approach, namely a legislative, conceptual and case approach. The result of the research from this thesis is that the legal certainty of land purchase and sale agreements carried out through name borrowing according to Article 1320 of the Civil Code requires four conditions, namely agreement, proficiency, certain objects, and halal causa. Although it meets the formal requirements, this agreement violates the requirements of halal causa, especially if it aims to grant land rights to parties prohibited by the Basic Agrarian Law (UUPA), such as Foreign Citizens (WNA). This violation causes the agreement to be null and void because it is contrary to the principle of freedom of contract as stipulated in Article 1337 of the Civil Code, which prohibits agreements with the aim of going against the law, public order, or morality. The notary's responsibility in making a name loan agreement through an authentic deed for an unlawful agreement can be subject to administrative, civil, or criminal sanctions.