A method of executing a handover between heterogeneous networks and method of supporting the same are disclosed, by which the handover can be smoothly performed between a wireless mobile communication network and a wireless LAN. A method of executing a handover between heterogeneous networks, in which a user equipment communicating with a wireless mobile communication network performs the handover into a wireless LAN, includes the steps of making a request for information for at least one cell neighbor to the wireless LAN to a second mobile communication network node via a first mobile communication network node, receiving the information for the at least one cell via the first mobile communication network node from the second mobile communication network node, and executing the handover to the wireless LAN using the received information.