A spherical annular seal member 39 includes a spherical annular base member 37 defined by a cylindrical inner surface 33, a partially convex spherical surface 34, and an annular end faces 35 and 36; and an outer layer 38 formed integrally on the partially convex spherical surface 34 of the spherical annular base member 37. The spherical annular base member 37 includes a reinforcing member 5 made from a metal wire net and a heat-resistant material 6 filling meshes of the metal wire net of the reinforcing member 5 and formed integrally with the reinforcing member 5 in mixed form. The outer layer 38 includes a base layer 46 and a sliding layer 40 constituted of a lubricating composition and adherently formed integrally on the base layer 46 at an outer layer intermediate surface 42, the base layer 46 including a reinforcing member 15 made from a metal wire net and compressed and a heat-resistant material 14 filling meshes of the metal wire net of the reinforcing member 15 and closely press bonded to the reinforcing member 1 S, the base layer 46 being formed integrally with the partially convex spherical surface 34.