A signal contact member and a ground contact member to which a center conductor and an outer conductor of a coaxial cable are connected are supported by an insulating housing member. The ground contact member has an annular fitting portion that fits and connects to the ground contact portion of a mate connector device. The annular fitting portion is provided with an opening for disposing a center conductor connection portion of the signal contact member. A shell portion of a ground contact member or an insulating housing member is provided with a conductive member given a ground potential. The conductive member partially fills the opening in the annular fitting portion.