Protecting the prosperity of merchants is a sort of support for a country's economy and this protection is of more significance when a trader is engaged in trading in a rented place, because the accumulation of defending the tenant's prosperity and landlord absolute ownership is challenging. In Iranian law, unlike France, the prosperity of a tenant is not protected independently and only a tenant who has the right to acquire or establish goodwill can redeem his business boom, and the prosperity of the tenants who lack the right to own or establish goodwill, even by having a good reputation, is not protected. But in French law, business prosperity is a property that can be bought, sold, rented, and mortgaged. This article seeks to prove that the basis of legal protection of rights such as the right to advance the business prosperity has existed in Islamic law before law of the west. Through a descriptive and interpretive method, it is attempted that while describing the procedure of protecting the prosperity of the tenant in Iranian and French laws and explaining the necessity of protecting this financial right in Islamic jurisprudence, the theory based on which it is possible to protect the prosperity of the tenant independently be presented; a theory in accordance with which if the landlord or the new tenant benefits from the former tenant’ s business prosperity, the former tenant is entitled to demand recompense for his financial right.