Abstract: A data relay device stores therein a total of costs between nodes in each of routes and, if a path having a predetermined bandwidth is to be established from a start node that is the device in a network to an end node, refers to the total cost while converging a number of routes required for obtaining the predetermined bandwidth, thereby virtually establishing one path. The data relay device includes a group organizing unit that organizes groups of routes such that a difference between total costs of the respective routes is equal to or less than a predetermined value preset in the data relay device; and a route selecting unit that selects a number of routes corresponding to the bandwidth of the path from an identical group in the groups organized by the group organizing unit in response to a request for establishing a path to the end node.