Mobile transaction system using dynamic track 2 data and method using the same

PURPOSE: A mobile payment system using dynamic track 2 information and a method thereof are provided to hide encoding and decoding processes of the track 2 information from other people and to secure high security. CONSTITUTION: When a request for track 2 information for mobile payment is received from a payment device (10), a dynamic primary account number (PAN) encoded except for a bank information number (BIN) and dynamic track 2 information including the dynamic PAN are formed. The dynamic track 2 information is transmitted to the payment device. When the dynamic track 2 information is received through a relay server (200), a PAN is extracted by decoding the dynamic track 2 information and a payment account of the payment device is determined by referring to the extracted PAN. [Reference numerals] (10) Payment device; (100) Mobile payment system; (200) Relay server; (50) Card reader slot; (AA) Require D-Track 2; (BB) Generate D-Track 2; (CC) Request for approval (D-Track 2); (DD) Write a message for the request for approval; (EE) Payment cost, information about a member store, D-Track 2; (FF,GG) Message for the approval request; (HH) Decode D-Track 2; (II) Determine validity and a payment limit; (JJ) Validity and the payment limit OK?; (KK) Approval message Y; (LL) Approval message; (MM,NN) Approval cancellation message