A card settlement method using a mobile information terminal provided with an IC card read/write function and a wireless communication function for the settlement of a transaction in a business establishment, comprising a step of having a customer using a business establishment wirelessly connect to an authorization server through a network by the mobile information terminal, a step of having the customer load his or her IC card in the mobile information terminal, read the information stored in this IC card, and send it to the authorization server, a step of having the authorization server decide on the authorization of the current transaction from authentication information stored in the IC card and proving the legitimacy of the card, settlement information containing at least a card number, and personal identification information input from the customer and proving the legitimacy of the customer, a step of sending a temporary password issued from a settlement server to the mobile information terminal for display after the authorization of the current transaction, a step of inputting the temporary password and the current transaction information from a business establishment side settlement terminal and sending it to the settlement server, and a step of having the settlement server settle the transaction with the password and the transaction information satisfying the settlement conditions.