System and method of providing service of simple payment

As without installing a security program for settlement, using a password generated by a simple payment application installed on the user terminal on the technical idea that provides the online payment of merchants, and express payment system in accordance with one embodiment is a user terminal If simple is the unique identification number of the app ID of the payment application related to the application registered at least one of the card user receives a password generation request including the card information selected as the method of payment of from, a random password to a secure random algorithm generating arithmetic unit, which when the said password through the redundancy check reply the password to the user terminal, and the processing unit put a time stamp stored in the database, and if the password received from the merchant with reference to the time stamp It includes parts of verification to determine if the password is valid, and returns the card to the merchant if valid.