A filter includes a first input/output electrode and the second input/output electrode, and is arranged on a first main surface of a mounting substrate. The mounting substrate includes a first land electrode, a second land electrode, a ground terminal, and a plurality of via conductors. The first land electrode is connected to the first input/output electrode. The second land electrode is connected to the second input/output electrode. The ground terminal is located closer to a second main surface side than the first main surface in a thickness direction of the mounting substrate. The plurality of via conductors is arranged between the first main surface and the second main surface, and is connected to the ground terminal. The plurality of via conductors is located between the first land electrode and the second land electrode in a plan view from the thickness direction of the mounting substrate.