Provided are a method and a system for providing a user tailored service using a social network service. The method includes at a user terminal, receiving a transaction approval message from a credit card company server when a customer uses a credit card, and obtaining purchase information of the customer based on the received transaction approval message, and forming a social network for sharing the purchase information of the customer with predetermined persons having a social relationship, wherein the predetermined persons include friends, family members, and colleagues of the customer.