Disclosed in the present invention is a method for supporting mobility of a mobile node between subnetworks in a wireless local area network that includes a plurality of subnetworks networked through Internet and assigns a different Internet protocol (IP) address to the plural subnetworks, respectively, the method comprising the steps of: if the mobile node moves arbitrarily to a second subnetwork from a first subnetwork during communication, broadcasting a first message, in which a foreign mobile access server (MAS) of the second subnetwork includes the mobile node's medium access control (MAC) address; acquiring, at a home mobile access server of the first subnetwork, an address of the foreign mobile access server from the first message, and then transmitting a second message including an address of the home mobile access server and an Internet protocol address of the mobile node to the foreign mobile access server in reply to the first message; and routing, at the foreign mobile access server and the home mobile access server, the mobile node's data by using the other party's address.