The present invention includes, a failure sensing part to sense the failure created in the encoder mode and sensorless mode to control the door; a main control part to convert the main operation part and backup control part mutually when a failure is sensed by the primary operation mode by the failure sensing part after deciding either of the encoder mode or sensorless mode as a primary operation mode and another one is decided as a backup operation mode; and a location/speed conversion part to perform the door control by calculating the door moving distance according to the corresponding mode when the operation mode is converted by the main control part.