A terminal substrate includes a signal terminal disposed on a terminal surface of an insulation ceramic layer. An insulation resin layer of a flexible substrate includes a first surface facing the terminal surface, and a second surface on an opposite side of the first surface. A first signal pad disposed on the first surface is joined to the signal terminal. A first penetration conductive part penetrates the insulation resin layer from the first signal pad. A first signal line is disposed on the second surface. A second penetration conductive part penetrates the insulation resin layer from the first signal line. A second signal line is disposed on the first surface. A third penetration conductive part penetrates the insulation resin layer from the second signal line. A second signal pad is disposed on the second surface.