A customer information database storing at least a unique customer identification number (basic pension number) allocated to the customers by an official body and information of an account number, an amount outstanding, password, and the like which correspond to the customer identification number are stored. An input screen control section controls screen display for inputting the customer identification number and the password. A control section performs authentication check based on customer information in the customer information database and the input customer identification number and the password as a key. A main control section performs various transactions at a financial institution on the basis of the result of the authentication.