A transmission line includes an insulator as a base member, a transmission conductor, and a ground layer. A connector is provided at a wiring substrate to fix the transmission line. The transmission line includes a signal columnar conductor having a solid columnar shape integrated with the transmission conductor, and ground columnar conductors having solid columnar shapes integrated with the ground layer. The connector has a through hole corresponding to the signal columnar conductor, and through holes corresponding to the ground columnar conductors. Conductive films are respectively provided on the inner peripheral surfaces of the through holes. The signal columnar conductor is inserted into the through hole, and the ground columnar conductors are respectively inserted into the through holes.