The monetary and banking law of Iran approved on 18/4/1351 has 45 articles. The first part of this law is about money. The problem and error in the definition of money is that a rial is not constant over time. Because the value of gold changes over time. As a result, the currency policy should be designed so that the value of one rial remains constant over time for all generations. That is, the value of money is in its purchasing power. In other words, the function of money is separate from the function of the monetary unit. That is, in the process of crediting money in economics, the monetary unit must also be credited. That is, the validity of money and the validity of monetary unit are necessary for each other. The role of currency in the exchange process is to give public awareness to all economic agents. In this new approach, the function of money is only a means of measuring value. That is, money does not store value in itself, but the monetary unit stores value in itself. Now, the monetary unit policy should be designed so that the value of a monetary unit remains constant over time for all generations. The solution is to create a public source of money, so that the ownership of this public source of money belongs to all generations. As a result of the act of providing money from this public source for all economic agents over time, it is in the form of a loan contract. In other words, the law should be changed as follows: one rial is equal to the provision of one unit of money from the general source of money in the form of a loan contract for all generations.