An amplification device includes a base substrate, an amplification element, and a matching circuit board. The amplification element is mounted on the base substrate. The matching circuit board is mounted on the base substrate and includes a circuit pattern which is electrically connected to the amplification element. The matching circuit board includes a first side surface and a second side surface each extending in the longitudinal direction of the matching circuit board. A first recess is provided in the first side surface. A second recess facing the first recess is provided in the second side surface.