According to the present invention provided is an accounting means that is superior in safety and usability. The accounting means comprises: payment means including a plurality of systems of communication means; charging means including a plurality of systems of communication means; and settlement means including a plurality of systems of communication means. Since the payment means and the settlement means exchange transaction data by communicating with each other, it is possible to prevent the assessment of an illegal charge by the charging means. In addition, since a signature (a digital signature) and an accounting statement are exchanged by communication between the payment means and the charging means, the efficiency of the sale can be improved.