To provide a welding structure which prevents the generation of a welding defect even when a certain degree of deviation of a position where the welding is required with respect to a welding torch happens in the axial direction in a welding structure for welding the external peripheral part of an annular body abutting along a spherical surface or a conical surface in a circumferential direction with respect to the spherical surface or the conical surface.

In a welding structure for welding the outer circumferential edge of an annular base part 6 of a driven plate 5 abutting along the spherical surface of a shell turbine 7 with the spherical surface of the shell turbine 7 along the circumferential direction with a welding torch 8, the outer corner part d on the opposite side of the inner edge c which is a position (a) where the welding is required is worked and formed lower toward the direction of coming farther from the welding torch 8 by working and forming the outer peripheral surface e of the annular base part 6 in a manner that the outer peripheral end surface e of the annular base part 6 becomes parallel with the axial direction of the driven plate 5 (and the shell turbine 7) in a state in which the inner edge side is left a little.