A computer executes a first determination procedure determining a first link which at least partially overlaps a disaster area representing a range reached by an influence of a predetermined disaster, among links constituting a network, a second determination procedure determining a second link which at least partially overlaps a road area representing a range of a road width of a predetermined road used to recover from the disaster, among the links constituting the network, a route search procedure searching for a plurality of routes from a start point node to an end point node constituting the network, a grouping procedure grouping the plurality of routes searched for by the route search procedure into groups depending on a first parameter value that is based on the first link included in the routes, a computing procedure computing, for each of the plurality of routes searched for by the route search procedure, a second parameter value that is based on the first link and the second link included in the routes, and a selecting procedure selecting a predetermined number of routes among one or more routes grouped into the same group on the basis of the second parameter value computed by the computing procedure for each of the groups grouped by the grouping procedure.