To allow a grounding element and a screw component made of different materials to be easily separated from each other without using any special tools or the like by providing an engaging mechanism between the grounding element and the screw component, and disengaging the engaging mechanism.

A screw component 4 has a mating part 6 which can mate in a recess 5 provided in a grounding element 2. An engaging mechanism 7 which, when the mating part 6 is integrally rotatably fitted into the recess 5, engages the mating part 6 to hold the screw component 4 and the grounding element 2 in mating positions to prevent removal of the mating part 6 from the recess 5 is provided between the mating part 6 and the recess 5.