There are provided a route search device and a computer program that can search for a recommended route for a user to move to a destination from a parking location after the user parks a vehicle in a parking lot. Specifically, a parking lot network is obtained which is a network representing a route that can be selected in a parking lot by the user with moving means used after getting out of the vehicle; an in-building network is obtained which is a network representing a route that can be selected in a building by the user with the moving means used after getting out of the vehicle; and a recommended route from a parking location where the vehicle is parked in the parking lot to a destination present in the building is searched using a network obtained by connecting the parking lot network to the in-building network.