The present invention enables a customer to conduct electronic commerce without divulging confidential information to vendors. The present invention is an electronic commerce transaction
system comprising a vendor terminal that has an
information transmission means that transmits electronic commerce transaction information, including at least information on the amount to be paid and the vendor identifier, a customer terminal used by the customer having a data-receiving unit for receiving said electronic commerce transaction information from said vendor terminal and a data-transmission unit for sending said electronic commerce transaction information, the customer's registered identifier, and a transaction
authentication code, and a financial institution terminal prepared in a financial institution with a data-receiving unit for receiving said electronic commerce transaction information, said customer's registered identifier, and transaction
authentication code, as well as a
database to specify the customer based on the registered identifier and to authenticate the customer based on the received transaction
authentication code, and wherein, said vendor terminal transmits electronic commerce transaction information to said customer terminal, said financial institution terminal receives the customer's registered identifier, and a transaction authentication code, and the electronic commerce transaction information from said customer terminal, and said
database of said financial institution terminal identifies the customer based on the registered identifier and authenticates the customer based on the received transaction authenticates code using said
database, and wherein, said financial institution terminal processes the
payment of the
payment amount to the vendor based on said electronic commerce transaction information, and withdraws the
payment amount from the customer's account or bills the customer for the payment amount.