A vehicular seat assembly is disclosed which comprises two seat sliders each including a lower rail secured to a vehicular floor and an upper rail sidably disposed on the lower rail; a seat frame securely mounted on the upper rails of the seat sliders; a seat cushion mounted on the seat frame; a side decorative panel attached to one lateral side of the seat frame for concealing unsightly portions; and a projection integrally formed on the side decorative panel, the projection being seated on the upper rail of one of the seat sliders.