An editing process including generation, modification, and deletion of pass points through which a linear structure such as a wire harness or the like should pass in a virtual space is performed in accordance with an operation of an input device by a user, a position of a pass point generated in the editing process is managed by using a plurality of position references to identify the position, and priority of the plurality of position references for each pass point are managed and a position of a pass point whose position has to be changed by an editing process is managed in accordance with the priority when the editing process is performed in accordance with an operation of the input device by a user.