A first board includes a first ground plane, a first ground land, a first transmission line, and a first signal land connected to the first transmission line, wherein the first ground land and the first signal land are formed on the same surface. A second board includes a second ground plane, a second ground land, a second transmission line, and a second signal land connected to the second transmission line, wherein the second ground land and the second signal land are formed on a surface opposing the first board. The second ground land and the second signal land oppose the first ground land and the first signal land, respectively. A conduction member connects the first ground land and the second ground land. The first signal land and the second signal land are connected by capacitance coupling without using any conductor.