To provide a method of controlling a router route that can use an unreliable router on a network and especially can reflect a change in a maintenance history immediately in order to select the router route appropriately.

Pieces of information 7', 8' on a maintenance history in routers 4, 5 adjacent to a router 3 are utilized, and a packet forward section 24 of the router 3 selects the router route according to the reliability of the routers 4, 5, thus allowing the unreliable router 4 to be used under a fixed situation. The router route is selected based on only the pieces of information 7', 8' on the maintenance history of the adjacent routers 4, 5, thus reflecting the change in the maintenance history immediately when the router route is selected.

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