Disclosed herein is a method and system for providing an international electronic payment service using mobile phone authentication. A payment method using an IPN server is selected, and results of verification of the product are relayed to a PG company server in a first country “A.” A user in country A enters primary authentication information, and a mobile communication company server performs primary authentication. The mobile phone of the user is then notified of an OTP, and the PG company server in country A receives the OTP and performs secondary authentication. The IPN server vicariously processes a payment between the PG company server and the mobile communication company server, and notifies a PG company server in a second country “B” of results of payment. The mobile communication company server sends paid money to the PG company server in country A, and the PG company server gives money corresponding to product price to the seller.