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), into which bent pieces (4a) formed at rear end of the decorative sheet (4) are inserted, are formed alternately on a rear side end of the sticking portion (3a). 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 upward. The bent piece (4a) of the decorative sheet (4) is thinner than a groove width at an upper part serving as an entrance part of the insertion groove (3c) and thicker than the groove width of a groove bottom-surface (3i) in the insertion groove (3c).