A clamp serves to fasten a shield member to a tubular portion of a shield shell using the elastic restoring force of the clamp. The clamp includes an annular clamp body and a pair of tabs. The tubular portion includes a tubular outer contour having two straight sections and two curved sections in a cross-sectional view. The clamp body includes a straight corresponding section corresponding to one of the straight section of the tubular portion and curved corresponding sections corresponding to the curved sections. The straight corresponding section is configured to bend less easily than the curved corresponding sections.