To realize a sufficient reduction in wind noise produced by a large insulator such as an insulator for salt-damage regions.

An elastic member is mounted on a ball-socket type link part of an insulator, and an elastic plug 40 is forced into an insertion hole 6 for a disconnection preventing pin 30 in the link part. Thus, the hole in the link part is closed, the absorbing efficiency of vibration caused by wind is enhanced, and the level of wind noise is reduced by several dB or more. The elastic plug 40 is larger than the insertion hole 6 for the disconnection preventing pin 30 and, when it is inserted together with the disconnection preventing pin 30, a side pressure acts on the insertion hole 6 for the pin 30, and therefore it serves as slip-lock of the disconnection preventing pin 30 and contributes to the enhancement of workability. The inserted state of the disconnection preventing pin 30 can be clearly checked by coloring the plug 40 with a conspicuous color (such as red) and forgotten insertion or insufficient insertion of the disconnection preventing pin 30 is noticed.