Provided is a settlement authentication method and system using a quantum random number generator. The method includes the steps of requesting, by a mobile terminal, a random number from a bank server and a POS terminal each including a quantum random number generator, periodically receiving a first quantum random number generated by the POS terminal and a second quantum random number generated by the bank server, and simultaneously sending a first quantum random number most recently received from the POS terminal to the bank server and a second quantum random number most recently received from the bank server to the POS terminal when the mobile terminal requests settlement.