In an accounting system, an user 1, by the use of a terminal 2, transmits a transmission packet P1 to a reception destination 3, that is a server of an information service provider, and receives a reception packet P2 therefrom by way of a packet communication network 4. The accounting apparatus 6 receives numbers of transmitted and received packets 51 from an exchange 5 and also receives the accounting amendment information 71 from the accounting amendment apparatus 7 at an adequate timing. The accounting apparatus 6 thereby decides the account fees for the user 1 of the terminal 2 and for the reception destination 3, respectively. In other words, the information service provider is charged with a part of the numbers of transmitted and received packets 51.