To eliminate troublesomeness in opening the rear end door for accom modation of a tonneau cover when the rear seat is tilted forward and the bag gage chamber is to be spread.

Slide parts at the two ends of a forefront bar 4 installed at the forefront of a sheet 2 are fitted on a pair of guide rails 3 which are mounted vertically on the left and the right side face of the tail of a baggage chamber L, and the bar 4 is moved automatically to the tops of the guide rails 3 when a rear seat back rest SR1 fitted with a retractor 1 capable of taking up the seat 2 is in upright attitude and the bar 4 is moved automatically to the bottoms of the guide rails 3 when the rear seat back rest SR1 is tilted forward.