A numerical controller includes a storage area for storing startable start-up settings and a database for storing start-up setting values that inhibit the completion of a start-up. If a start-up has been completed at the time of start-up, current start-up settings are stored in the storage area as startable settings. If the start-up has not been completed, start-up setting values that inhibit the completion are registered in the database, the current settings are reconstructed to startable settings, and the numerical controller is restarted. After start-up settings are changed, the database is searched. If the same start-up settings as the changed start-up setting are found, the found start-up settings are outputted.