In a lawful interception system including an interception unit, an application service providing unit, and an Internet access service providing unit, the application service providing unit may receive, from the interception unit, an interception request including interception target information of an interception target. Next, the application service providing unit may transfer a user code corresponding to the received interception target information to the interception unit, and may insert user related information into a packet to be provided to the interception target corresponding to the user code, enabling the packet to be lawfully intercepted. The interception unit may request the Internet access service providing unit for an interception of the packet with respect to the interception target by including the user code.