PURPOSE: To simply and inexpensively manufacture a sealing ring to be used when a cable interposed between members to be connected by a screw is clamped to be held.

CONSTITUTION: A cylinder 3 formed of rubberlike elastic material so as to exhibit a pure cylindrical shape is prepared. Outer and inner peripheral surfaces of the cylinder are inverted against an elasticity. A sealing ring 1 exhibiting a convergent-divergent shape, in which inner and outer diameters at an axial central part 1a are smaller than at booth end sides and both the ends 1b, 1c are radially outwardly raised, is manufactured.