A network-adaptive function control method is provided for a dual-mode mobile terminal. The network-adaptive function control method for a dual-mode mobile terminal supports communication via first and second-type networks includes registering at least one function as a network-adaptive; determining, when a function is requested to be activated, whether the requested function is the network-adaptive function. If it is determined that the requested function is the network-adaptive function, it if determined whether the mobile terminal is in the first-type network; and activating, if the mobile terminal is in the first-type network, the requested function in association with the first-type network. The network-adaptive function control method of the present invention allows registering portable IP network-friendly functions that are served only in a portable IP network domain but not in the cellular network domain, thereby restricting handover to the costly cellular network, resulting in reduction of communication cost.