Abstract: A charging method for readily settling payment. A mobile phone (30) accesses a center server (10) so as to input a command to purchase a serial number priced at 80 yen. The mobile phone (30) downloads the serial number and displays it as in the form of “SNxxxx”. At this time, 80 yen is added to the charge on the mobile phone. A client PC (20) accesses the center server (10), displays the page which is the entrance for displaying a pay content, allows the user to input the serial number displayed on the mobile phone (30) on the page through, e.g., the keyboard of the client PC (20) so as to transmit the serial number. On receiving the serial number, the center server (10) transmits the page information on the pay content to the client PC (20) when the received serial number coincides with the serial number transmitted to the mobile phone (30).