Provided is a spiral wound gasket which not only exhibits sealing properties, but also has a low risk of filler fracture, even after being used in a high-temperature atmosphere for a long period of time. This spiral wound gasket is provided with a gasket body formed by superposing a filler material and a hoop material and winding said materials into a spiralling shape. The spiral wound gasket is characterized in that: the filler material comprises a sheet including inorganic fibres, and when a rectangular parallelepiped test piece having dimensions of 30 mm (long sides)×15 mm (short sides), and a thickness of 0.5±0.05 mm is extracted from the filler material, heated at 500˚C for 96 hours, and subsequently placed on two rods separated by an interval of 14 mm such that the short sides are parallel with the rods and the centre of the test piece overlaps the centre of the interval, and a rectangular parallelepiped weight having a weight of 1 g, and dimensions of at least 9 mm (short sides)×15 mm (long sides), is placed on the centre of the test piece such that the central axes of the respective long sides of the test piece and the weight intersect, and the test piece can hold the weight for 5-10 seconds without breaking, the strength is deemed to be 1 g, and when the filler strength is defined as the weight of the weights that can be held by the test piece until just before the test piece breaks after repeatedly having 1 g weights further placed thereon and holding said weights for 5-10 seconds, the filler strength is at least 9 g.