There is provided a method of processing Internet Protocol (IP) handoff of a mobile node in a network system, in which the IP handoff is processed distinguishing a signal packet path for the IP handoff from a data packet path the method including receiving a registration request message when the mobile node moves to an arbitrary mobile agent, the message received from the mobile node via the mobile agent to which the mobile node moves; transmitting the received registration request message to a mobile agent where the mobile node is previously located, without change, according to whether an entry with respect to the mobile node exists in preset visitor list; and transmitting a registration reply message with respect to the registration request message to the mobile agent without change.