PROBLEM TO BE SOLVED: To provide a credit card system which allows a supporting party to easily use it and a supported party to use it without any plea or concern.SOLUTION: A supporter registers an identification number of a credit card of a supported person that the supporter wants to support and support conditions defining conditions which allows the support (such as a support limit amount) in a system of his/her own credit card company. When the registered supported person actually shops by using his/her own credit card, a system of an affiliated shop where he/she shops transmits a card authentication request to the system of the credit card company. This system determines whether the purchase of the supported person satisfies the support conditions and when determining that the conditions are satisfied, a part or all of the payment of the purchase price is authenticated with a credit card of the supporter and charged.
