An apparatus for distributing data traffic in heterogeneous wireless networks is provided to enable a terminal and a network to share the data transmission rules by which the terminal accessing the heterogeneous wireless networks transmits data based on the distribution to the heterogeneous wireless network. Terminals(110,150,160,170) that are able to transmit data to plural wireless networks include a transmission rule storage unit, a data division unit, a transmission network selector and a network connector. The transmission rule storage unit stores the transmission rules for the plural wireless networks. The data division unit divides the first data into firs data group based on the stored data transmission rule. The transmission network selector selects a transmission network for each data group among the wireless networks based on the determined data transmission rule, and the network accessing unit transmits each data group to the selected transmission network.