A route search system, a route search method, and a computer program capable of finding a more appropriate route for a user are provided. A probe center 4 collects probe information from vehicles 3 that travel across the country, and a navigation apparatus 2 calculates the link cost of a link on the basis of the probe information in the case where a search for a recommended route is performed (S2). The reliability degree of the calculated link cost is specified on the basis of the number of pieces of the probe information used to calculate the link cost of the link (S3). The value of the link cost, the reliability degree of which has been specified, is corrected on the basis of the specified reliability degree (S6). A search for a recommended route is performed using the corrected value of the link cost (S7).