A navigation server and the like capable of making a navigation device 200 output a route having adequacy in view of various circumstances is provided. A navigation server 100 recognizes a navigation route r(k) for guiding the automobile 2 to the destination position p2 which is set according to the first algorithm by the navigation device 200. Further, a support route R(k) for guiding the automobile 2 from a current position (or a departure position) p1 to the destination position p2 which is set according to the first algorithm is recognized. Still further, a first index c1(k) representing an adequacy of the navigation route r(k) in view of the second algorithm is evaluated. On condition that the first index c1(k) satisfies a predetermined condition, the support route R(k) is output in place of the navigation route r(k) by the navigation device 200.