Abstract: The present invention relates to an automatically operated opening and closing roof composed of a sheet or tarpaulin; a frame constituting the whole rim of the roof; a drum supported rotatably on the frame and holding an end of the sheet whereby allowing it to roll out and roll up the sheet; a slider holding the other end of the sheet and slidably supported by a guide rail which is mounted on the frame for allowing the slides to move toward and away from the drum; and an actuator mounted on the frame for driving the slider and/or the drum along the guide rail whereby covering over the frame with the sheet or uncovering the frame. A rain sensor for detecting rain, snow and other wetness; and a controller for switching the actuator on when a signal reaches it from the rain sensor are used for covering the sheet over the frame, and counter-switching the actuator when a reverse signal reaches the controller when the rain stops, thus uncovering the sheet from the frame.