There is provided a plain-weave fabric excellent in low air permeability and waterproofness. Further, there is provided a stent graft excellent in low water permeability mechanical properties and catheter storage capacity, including the plain-weave fabric as a graft substrate. A plain-weave fabric woven by interlacing weaving yarns in warp and weft, in which weaving yarns YA and YB arranged in the same direction have different crimp ratios A and B, respectively, a relationship thereof satisfies Formula 1, and the crimp ratio B is 4% or more, and the plain-weave fabric is preferably used for a stent graft; A≥B×1.2.