A temporal engaging portion is provided at a bin. Therefore, by engaging a bin-side arm with a bin-side engaging portion and temporally engaging a panel-side arm with the temporal engaging portion after elastically deforming the panel-side arm, a torsion spring can be set to the bin before the bin is coupled with a panel. The bin set with the torsion spring is inserted into a recess of the panel. During rotation of the bin toward a closed position, a temporal engagement of the panel-side arm with the temporal engaging portion is released, and upon being released, the panel-side arm is elastically sprung-back to be finally engaged with the panel-side engaging portion. As a result, by only coupling the bin set with the torsion spring with the panel, the bin and the torsion spring can be coupled with the panel so that coupling work is improved.