There are provided a method and an apparatus for transmitting an IP packet using segment routing. A path controller for transmitting an IP packet in a mobile communication system including heterogeneous networks includes a data transmission path establishing module configured to, if a request message for establishing a data path is received from any one of a plurality of mobile nodes, determine transport nodes that the IP packets is traverse between mobile nodes, and transmit segment values corresponding to the determined transport nodes to the mobile nodes sending the request message for establishing the data path, wherein the plurality of mobile nodes are connected to transport nodes and there may be a lot of data paths between them.