When a multipolar plug and a counter connector are fitted to each other, there is a possibility that a seam joint of a shell of the multipolar plug may coincide with that of a shell the counter connector, and high-frequency noises may leak through gaps of the coincident seam joints. The invention has been conducted in view of the problem, and provides a multipolar plug which can improve the EMI characteristics of a multipolar connector. According to the invention, when the multipolar plug 2 and the counter connector 4 are fitted to each other, the seam joint 9a of the shell 9 of the multipolar plug 2 is shifted from a seam joint 17a of a shell 17 of the counter connector 4.