To deal with it even if the guide groove width on the lower end of a hanger door is changed by changing the guide width of a head part through the change of the direction of a bracing device.

This bracing device is formed out of a base 11, a body part 12, and a head part 13. The head part 13 is constituted of four guide projecting pieces 14a, 14b, 15a, 15b, and the respective guide projecting pieces are at right angles to each other to extended outward. The projecting length of the projecting pieces 14a, 14b are made equal to each other and they are made symmetric against the center axis. Similarly the projecting pieces 15a, 15b are made equal in the projecting length and symmetric against the center axis. At this time, the projecting length of the projecting pieces 14a, 14b are made longer than the projecting pieces 15a, 15b. Accordingly, the bracing device having two sorts of guide width is provided. Hereby, even if the guide groove width of a hanger door is changed, it can deal with it, and because the head part can be arranged without gap against the guide groove width, side runout of the hanger door is eliminated, and the door can be smoothly opened/closed.