A surface structure of wadded seat, with a trim cover having a plurality of trim cover pieces backed with wadding members and sewed together at ends, further includes: first sewed portions, each formed by sewing two adjacent trim cover pieces at one end of each trim cover piece, while serving as seam allowance, the portions not backed with the wadding members; second sewed portions, each formed first by forming a continuous trim cover piece, then by laying a long wadding member on the backs of the wadding members, and finally by sewing, at both ends of the continuous trim cover piece, the wadding members on the backs of the trim cover pieces and the long wadding member; and third sewed portions, each formed by sewing, at both ends of each first sewed portion, the long wadding member to the end of each trim cover piece.