A dynamic packet relay method of a personal area network (PAN) coordinator in a sensor network includes receiving a Child_Register message that includes information about a device associated with a coordinator and building or updating a network hierarchical structure; monitoring reception of a packet or a beacon from the coordinator and determining whether the coordinator is defective or not; and in response to a determination that the coordinator is defective, changing the current coordinator to one of devices belonging to a PAN as a new coordinator.