It is to improve the robustness and the data transfer reliability of a network.When the destination node is the sixty sixth wireless device D66, the second wireless device D2 determines that there is no destination node among neighboring nodes based on the parent-and-child-node information of the first neighboring node information to transfer the data to the first wireless device D1 as a parent node. The first wireless device D1 can communicate within a communicable range AR1 and memorizes network information of the zeroth wireless device D0, the second wireless device D2, the seventh wireless device D7, the eighth wireless device D8, and the seventeenth wireless device D17. The first wireless device D1 determines that the sixty sixth wireless device D66 as a destination node exists at the neighborhood of the seventh wireless device D7 to transfer the data to the seventh wireless device D7. Then, the seventh wireless device D7 determines that the sixty sixth wireless device D66 as a neighboring node is the destination node to transfer the data to the device.