According to the present invention, when electronic money is sent from a given network to another network, a money change apparatus performs a money change process to change electronic money current on the given network into electronic money current on another network, and therefore when a user of the given network uses a settling process, by managing this money change process, it is possible to manage the interchange of electronic money between each of the users of the given network and each of the users of another network without affecting the working environment of electronic commerce. Electronic money current on LAN20 is referred to as local electronic money current only on the network. When a terminal NLU4 connected to LAN20 sends money to a terminal NWU2 connected to WAN10, GW1 for controlling the flow of data between LAN20 and WAN10 receives local electronic money sent from the terminal NLU4, changes the local electronic money into electronic money current on WAN10, then sends the electronic money to the terminal NWU2, and when a terminal NWU2 sends money to a terminal NLU4, GW1 receives electronic money sent from the terminal NWU2, changes the electronic money into local electronic money and sends the local electronic money to the terminal NLU4.