The method for turning off the power automatically if no image signal or key is input for preset time even though the switch is on includes the steps of: a) determining the existence of the image signal during the switch-on state; b) turning off the power after preset time if the signal is not received any more; c) checking the key input for preset time if there is the image signal and turning off the power if no; and d) keeping the power-on state if there is image signal or key input during the preset time.
