Disclosed is a connector 100 which has a center contact 20 electrically connected to an inner conductor formed of a corrugated duct, a tubular body 60 electrically connected to an outer conductor and surrounding the center contact 20, and an insulating member 70 by which the center contact 20 and the tubular body 60 are insulated electrically from each other. The center contact 20 is provided with an external thread part 22 which is brought into mating engagement with the inner conductor, and the external thread part 22 has a first external thread of a first pitch shorter than the pitch of the corrugated duct.