Abstract: A device and method for forming a trim cover assembly for an automotive seat, wherein a top cover layer is stretched and pressed on a lower die by plural upper die elements in the outward direction and symmetrically relative to a central line of the lower die, to thereby place the top cover layer without clearance and slackened area therein, upon the lower die, and then a foam wadding and a wadding cover are fixed to the thus-pressed top cover layer. Thus, the resulting trim cove assembly is formed with a clear-cut or very distinct pattern of recessed grooves thereon.