Miftahuddin 34.3.2.11325 Money is a recognized medium of exchange worldwide. The history of money itself has a very long story. Almost every country has its own currency that is different from other countries. Based on its function, the main function of money is as a medium of exchange. But lately the researcher found that money is no longer used as its original function as when money was first created. So that various problems arise in this world, both in the micro and macro scope. Ibn Khaldun and Al-Ghazali are two classical Islamic scholars who often mention about researcher economics, specifically about money and its functions. Both opinions are often used as reference material by Shariah economists today in various discussions. Seeing money that should be a solution to problems that occur in society, but precisely this time money is a source of global problems, in this research the researcher wants to know the opinion of Ibn Khaldun and Al-Ghazali about the notion of money and its function, as well as the similarities and differences between the two opinions. The method used by the researcher is the literary and documentary method to find out the life history of Ibn Khaldun and Al-Ghazali, their essays and thoughts that concerned with the discussion of this research. Then analyzed by the inductive method of drawing conclusions from their second view of economic understanding in general, then by deductive methods of drawing conclusions about money and its function according to both of them. Then with a comparative method to compare the opinions of both so that the similarities and differences between the two are clear. With these three methods, the researcher can conclude that they both differ in opinions regarding the use of paper money (fiat). Ibn Khaldun allowed the use of banknotes (fiat) on the condition that there were gold reserves or collateral in the bank. Whereas Al-Ghazali permits the use of paper money (fiat) without gold or silver guarantees provided that the government states paper money is an official payment instrument, the government must maintain its value, and ensure there is no money trading. But both agreed that money, gold and silver had no intrinsic element, and the government or the king has the right to print and circulate banknotes, the prohibition of usury practices and counterfeiting of money, and make the main function of money as a medium of exchange. Keywords: money, function of money, medium of change