A new transfer apparatus (Nn) not included in a first network but in a second network for migration of a service over the first network to the second network, the first network having a configuration in which a cost required for data transfer is set to each of links coupling an existing transfer apparatus to another existing transfer apparatus, and data is transferred along a route that has been set based on a sum of the costs, said new transfer apparatus (Nn) comprising: a processor for executing programs; and a memory for storing the programs, wherein the processor comprises: first calculation processing means adapted to calculate a total cost of a first route in the first network that starts from an existing source transfer apparatus and ends at an existing destination transfer apparatus; obtaining processing means adapted to obtain a particular cost, the particular cost being a cost between the existing source transfer apparatus and a first link, which couples the existing source transfer apparatus and the new transfer apparatus (Nn), in a second route, which starts from the existing source transfer apparatus and reaches the existing destination transfer apparatus via the new transfer apparatus (Nn); second calculation processing means adapted to calculate a differential between the total cost calculated in the first calculation processing and the particular cost obtained in the obtaining processing; setting processing means adapted to set, based on the differential calculated in the second calculation processing, a cost between the new transfer apparatus (Nn) and a second link, which couples the new transfer apparatus (Nn) and the existing destination transfer apparatus, to a value smaller than said differential that was calculated in the second calculation processing if a lower-cost route is to be selected or to a value higher than said differential that was calculated in the second calculation processing if a higher-cost route is to be selected; and notification processing means adapted to notify the cost value set in the setting processing to the existing source transfer apparatus. a processor for executing programs; and a memory for storing the programs, wherein the processor comprises: first calculation processing means adapted to calculate a total cost of a first route in the first network that starts from an existing source transfer apparatus and ends at an existing destination transfer apparatus; obtaining processing means adapted to obtain a particular cost, the particular cost being a cost between the existing source transfer apparatus and a first link, which couples the existing source transfer apparatus and the new transfer apparatus (Nn), in a second route, which starts from the existing source transfer apparatus and reaches the existing destination transfer apparatus via the new transfer apparatus (Nn); second calculation processing means adapted to calculate a differential between the total cost calculated in the first calculation processing and the particular cost obtained in the obtaining processing; setting processing means adapted to set, based on the differential calculated in the second calculation processing, a cost between the new transfer apparatus (Nn) and a second link, which couples the new transfer apparatus (Nn) and the existing destination transfer apparatus, to a value smaller than said differential that was calculated in the second calculation processing if a lower-cost route is to be selected or to a value higher than said differential that was calculated in the second calculation processing if a higher-cost route is to be selected; and notification processing means adapted to notify the cost value set in the setting processing to the existing source transfer apparatus. first calculation processing means adapted to calculate a total cost of a first route in the first network that starts from an existing source transfer apparatus and ends at an existing destination transfer apparatus; obtaining processing means adapted to obtain a particular cost, the particular cost being a cost between the existing source transfer apparatus and a first link, which couples the existing source transfer apparatus and the new transfer apparatus (Nn), in a second route, which starts from the existing source transfer apparatus and reaches the existing destination transfer apparatus via the new transfer apparatus (Nn); second calculation processing means adapted to calculate a differential between the total cost calculated in the first calculation processing and the particular cost obtained in the obtaining processing; setting processing means adapted to set, based on the differential calculated in the second calculation processing, a cost between the new transfer apparatus (Nn) and a second link, which couples the new transfer apparatus (Nn) and the existing destination transfer apparatus, to a value smaller than said differential that was calculated in the second calculation processing if a lower-cost route is to be selected or to a value higher than said differential that was calculated in the second calculation processing if a higher-cost route is to be selected; and notification processing means adapted to notify the cost value set in the setting processing to the existing source transfer apparatus.