An electronic settlement system for settling a transaction through a communication network comprises a settlement apparatus which performs the settlement of the transaction; a billing terminal connecting to the settlement apparatus via the communication network; and a paying terminal, connecting to the settlement apparatus via the communication network, wherein the settlement apparatus performs the settlement of a transaction by synchronizing a communication to the billing terminal with a communication to the paying terminal when the settlement apparatus sets up a transaction identifying number which identifies the transaction and when the paying terminal transmits the same transaction identifying number to the settlement apparatus.