A seat, comprising: a seat cushion unit including: a seat cushion frame; a seat pad which lies over the seat cushion frame; and a trim which covers the seat pad, wherein the trim includes: a trim main body which mainly covers a top surface of the seat pad; a first trim joiner which extends from the trim main body to a backside of the seat cushion frame at the rear of the seat pad, and is fastened to the seat cushion frame; and a second trim joiner which is connected to a back surface of the trim main body in at least one of left and right end regions of the rear of the seat cushion unit, extends to the backside of the seat cushion frame at the rear of the seat pad, and is fastened to the seat cushion frame, and wherein the seat cushion unit includes a sitting part for supporting buttocks of an occupant, and a bulge part extending in a front-rear direction on each of left and right sides of the sitting part, the trim main body has a pull-in section which extends along a boundary between the bulge part and the sitting part, and is pulled into the seat pad side, and the second trim joiner is connected to the pull-in section, and it is characteried in that the second trim joiner extends along a side pull-in section of the pull-in section that extends in the front-rear direction along the bulge part, and is connected to the side pull-in section. a seat cushion frame; a seat pad which lies over the seat cushion frame; and a trim which covers the seat pad, wherein the trim includes: a trim main body which mainly covers a top surface of the seat pad; a first trim joiner which extends from the trim main body to a backside of the seat cushion frame at the rear of the seat pad, and is fastened to the seat cushion frame; and a second trim joiner which is connected to a back surface of the trim main body in at least one of left and right end regions of the rear of the seat cushion unit, extends to the backside of the seat cushion frame at the rear of the seat pad, and is fastened to the seat cushion frame, and wherein the seat cushion unit includes a sitting part for supporting buttocks of an occupant, and a bulge part extending in a front-rear direction on each of left and right sides of the sitting part, the trim main body has a pull-in section which extends along a boundary between the bulge part and the sitting part, and is pulled into the seat pad side, and the second trim joiner is connected to the pull-in section, and it is characteried in that the second trim joiner extends along a side pull-in section of the pull-in section that extends in the front-rear direction along the bulge part, and is connected to the side pull-in section. a trim main body which mainly covers a top surface of the seat pad; a first trim joiner which extends from the trim main body to a backside of the seat cushion frame at the rear of the seat pad, and is fastened to the seat cushion frame; and a second trim joiner which is connected to a back surface of the trim main body in at least one of left and right end regions of the rear of the seat cushion unit, extends to the backside of the seat cushion frame at the rear of the seat pad, and is fastened to the seat cushion frame, and wherein the seat cushion unit includes a sitting part for supporting buttocks of an occupant, and a bulge part extending in a front-rear direction on each of left and right sides of the sitting part, the trim main body has a pull-in section which extends along a boundary between the bulge part and the sitting part, and is pulled into the seat pad side, and the second trim joiner is connected to the pull-in section, and it is characteried in that the second trim joiner extends along a side pull-in section of the pull-in section that extends in the front-rear direction along the bulge part, and is connected to the side pull-in section.