A plurality of signal terminals are disposed in parallel and comprise an embedded part embedded and held in a base member of insulating material and a protruding part that protrudes from the base member, the protruding part forms a connecting part that is electrically connected by contacting or solder-connecting to a mating connecting body, the base member comprises a main body holding part that covers the entire circumference of the circumferential surface of the signal terminals and holds the signal terminals, and a semi-exposed holding part that exposes a portion of the circumferential surface of the signal terminals while covering and holding the remaining portion, with the protruding part of the signal terminals protruding from the semi-exposed holding part with regard to the main body holding part.