PURPOSE: To secure the stable operation and eliminate the chattering due to air resistance by slightly lifting up and supporting the whole and lifting up the rear edge, in setting a cover member to a tilt-up attitude from a perfect closure attitude.

CONSTITUTION: The right and left lifters 18 in pair are installed onto a cover member 7 for opening and closing an opened port part 12 formed on the roof 2 of an automobile, and a pair of guide rails 11 are installed onto both the sides of the opened port part 12. A cam mechanism 28 having the front and rear grooves 26 and 27 in pair are installed between a slider 20 which is slidingly moved along each guide rail 11 and the lifter 18, and the cover member 7 is raised in up-tail form with the rearward shift of the slider 20 by the action of the cam mechanism 28, and then shifted rearward. An engaged part 34 is formed on the guide rail 11, and a position setting member 31 is installed in demountable manner on the engaged part 34, and a front guide means 35 which permits the vertical movement of the lifter 18 and restricts the longitudinal movement is installed between the position setting member 31 and the lifter 18.