A pull-in recess is formed in a seat pad (30). The pull-in recess is partly formed as a through hole penetrating to a back surface of the seat pad. A seat cover (40) is formed into a bag shape. A string-shaped member (50) for drawing the seat cover (40) and attaching the same to the seat pad (30) is disposed along an opening of the seat cover. The seat cover (40) is provided with a pull-in portion at a position corresponding to the pull-in recess of the seat pad (30). The pull-in portion is inserted into the through hole of the seat pad (30). A distal end of the pull-in portion is provided with a retainer portion (47a and 47b) that is capable of engaging the string-shaped member (50). The retainer portions (47a and 47b) inserted into the through holes (34a and 34b) of the seat pad (30) are engaged with the string-shaped member (50) while the drawing action force of the string-shaped member (50) is applied thereto, which force can be produced when the seat cover is attached by drawing.