a method and apparatus for supporting a seamless handover in a transport layer is provided . in a network using an sctp , an mn notifies a cn of a handover after the handover occurs . the mn receives a handover confirm message from the cn and sends a response message for the handover confirm message to the cn . the mn checks a recipient ip address at which data is received from the cn . if the recipient ip address is a new ip address , the mn changes a primary ip address of the mn to the new ip address . if the recipient ip address is the primary ip address , the mn maintains the primary ip address .