A vehicular seat capable of reducing a tensile force, which acts on a sewing thread in a webbing sewn part, enables desired expanding operation of a side air bag in the case of emergency. The vehicular seat has an air bag body, provided in the side part of the seat back, which tear-opens the extending part of the trim cover by expansion, to expand from the seat back. A wrap-sewn part, with its terminal end wrap-folded, is provided at an end sewn to the trim cover. The wrap-sewn part has an overlap part where the webbing is overlapped, and a non-overlap part provided at an end of the overlap part in a direction along a sewing line of sewing to the trim cover. The wrap-sewn part is sewn over the overlap and the non-overlap part with respect to the trim cover.