A sliding structure slidably supports a wheel by a groove of a rail. The wheel is rotatably supported to a movable console through a supporting shaft. The sliding structure includes an elastic deforming portion which is elastically deformed when an overload is vertically applied to the movable console and is restored to the original state when its application ceases; an ascending/descending portion which descends with elastic deformation of the elastic deforming portion and ascends with restoration; and a bottom of a tray serving as a pressure receiving portion, which is provided on an ascending/descending path of the ascending/descending portion and comes in contact with the ascending/descending portion 79 descended to receive a part of the overload.