To set up charging amounts of money on a provided service for every user in accordance with users' demands.

A user requests a service through a terminal 20. According to a request signal from the terminal 20, a communication relay unit 31 relays and connects a communication addressed by the terminal 20 to inform also an accounting unit 10 of the utilization start of the service. The informed accounting unit 10 previously stores station data of predetermined accounting data and accounting data for every subscriber in a data unit 13. The terminal 20 receives a message to previously show a probability determined for an accounting rate contained in the accounting data. The user selects to draw lots. The accounting rate is determined and stored in the data unit 13 to calculate the accounting amount and inform the terminal 20 thereof. The accounting amount is saved in an accounting meter 14. A timer 12 periodically starts a specified process to determine the accounting amount and the accounting rate by drawing lots.