A temporary fixing unit includes a supporting portion including a distal end portion passed through an aperture, and a holding portion provided with an inclined surface that slides along an edge portion of the aperture when passed through the aperture. The temporary fixing unit also includes a spring portion connecting the distal end portion of the supporting portion and the holding portion and that deforms in a twisted manner as the holding portion is pushed down when the inclined surface of the holding portion slides along the edge portion of the aperture. When the holding portion is passed through the aperture, a portion of a door panel is held between the holding portion and an elastic portion. Furthermore, the elastic portion is elastically deformed so as to press the door panel.