A card to card transfer method used in the financial system is provided in the present invention, and comprises an initializing step, a transferring step and a transaction confirming step, wherein the initializing step includes the steps of calculating and obtaining the public key certificate and checking the amount of the transaction and so on, and the transferring step includes the steps of performing the transaction and so on. The present invention can achieve the function of transferring the electronic cash between two cards and can prevent the risk of repeatedly transferring the money into the card for transfer-in by using the card for transfer-out and so on.