Transmission apparatus with plural network interface and transmission method of using the same

A transmitting apparatus and a method with plural network interfaces are provided to secure an optimal communication performance in a multi-mode contemporaneous connection environment by distributing traffic to plural network by service. A transmitting apparatus with plural network interfaces includes a session information extracting unit(100), a network interface determining unit(110), and a traffic allocating unit(130). The session information extracting unit extracts session information of an IP packet. The network interface determining unit determines the network interface corresponding to the session information of the IP packet based on a table mapped with the session information and the network interface according to an available band width of each network interface. The traffic allocating unit transmits the IP packet to the determined network interface.