Provided is an information processing device which enables a user to always and easily recognize an amount to be paid by the user, which results in a reduction of the burden imposed on the user. A debit requesting module (72) requests that a bank debit a bill amount of each transaction of a credit card from a payment account of the credit card. A balance determination module (81) determines whether or not a balance of the payment account is insufficient for the bill amount of the each transaction based on a notification of a result of the debit from the bank. A change module (74) changes, when it is determined that the balance of the payment account is insufficient, a payment method for a bill amount of an item of transactions which uses a variable payment method to a fixed payment method, the fixed payment method being a method of paying a predetermined fixed amount of money as a unit, the variable payment method being a method of making a payment with a payment unit that varies for each transaction depending on an amount of the transaction of the credit card. The present invention is applicable to a server.