1. An IP (Internet protocol) handoff method comprising: receiving an IP handoff registration request message from an FA (foreign agent) of an MN (mobile node) by a mobile agent platform (MAP) and determining whether or not the MN moves in the MAP; when it is determined that the MN moves from another MAP, transmitting a message for requesting to add an entry of the MN to a border list of the another MAP; and when it is determined that the MN moves in the same MAP and the FA is adjacent to the another MAP, transmitting a message for requesting to add the entry of the MN to the border list of the another MAP.