Abstract: The present invention is an integrated authentication system managing a process of conclusion of an electronic contract by communicating the electronic contract concluded at a mobile terminal with an integrated authentication server, the integrated authentication system comprises the electronic contract for electronically concluding a contract; the mobile terminal for downloading the electronic contract from the integrated authentication server, concluding a contract electronically, and transferring the concluded electronic contract to the integrated authentication server; and the integrated authentication server for transferring the electronic contract to the mobile terminal, receiving the electronic contract concluded from the mobile terminal, and managing the process of concluding the electronic contract, wherein the integrated authentication server comprises: a form-design unit for making an image of the electronic contract, and designing the form of the electronic contract; a log-in managing unit for aut