A directional coupler includes a main line, a sub line, and a parasitic element. The main line includes first and second main line portions formed substantially in a spiral shape, as viewed from a first direction. The second main line portion is positioned in a second direction which is perpendicular to the first direction, as viewed from the first direction. The sub line includes first and second sub line portions formed substantially in a spiral shape, as viewed from the first direction. The first and second sub line portions are electromagnetically coupled with the first and second main line portions, respectively. The second sub line portion is positioned in the second direction, as viewed from the first direction. The parasitic element is superposed on the first main line portion and the second sub line portion, as viewed from the first direction.