A closure device for closing an access opening in a motor-vehicle body. An inner chamber is accessible via the access opening and the access opening can be closed by a cap element. The cap element is connected to a guide device, which is arranged in the inner chamber and via which the cap element can be adjusted between a closed position and an open position. The guide device is configured such that the cap element executes a pushing movement and a lifting movement as it moves between the closed position and the open position. The cap element, in the open position, is arranged in the inner chamber.