An instrument panel unit (2) includes an instrument panel (3) and a decorative sheet (4). The instrument panel (3) includes a sticking portion (3a) and an exposed portion (3b). A plurality of insertion grooves 3c and insertion holes 3d are formed alternately at an end on a rear side of the sticking portion (3a), into which bent pieces (4a) formed at a rear end of the decorative sheet (4) are inserted. A groove front-surface (3g) forming the insertion groove (3c) of the instrument panel (3) is formed in a tapered shape such that a width between the groove front-surface and an opposing groove rear-surface (3h) gradually increases upwardly. The bent piece (4a) is formed to be thinner than the groove width at the upper part serving as the entrance part of the insertion groove (3c) and to be thicker than the groove width of a groove bottom-surface (3i).