A long door, particularly for a four-passenger cope vehicle, is provided to allow passengers in the back seat to get in or out while the passengers in the front seat remain seated. An intermediate member stands between a door and a car body. A first connection member in which the door and the intermediate member are connected to enable rotational or horizontal motion, and a second connection member in which the intermediate member and the car body are detachably connected are provided. A control drives the second connection member located at the front or back end of the door when the front or back part of the door is opened, so that the connection between the intermediate member and the car body is released and the remaining second connection member, the intermediate member connected to that member, and the first connection member cooperate to support the weight of the door.