A directional coupler includes a multilayer structure formed by stacking a plurality of dielectric layers including first and second dielectric layers; a main line including first and second main line portions that are electrically connected in series to each other; and a sub line electromagnetically coupled with the main line, the sub line including first and second sub line portions that are electrically connected in series to each other. The first main line portion and the first sub line portion are provided on the first dielectric layer. The second main line portion and the second sub line portion are provided on the second dielectric layer. In planar view along a stacking direction, the first main line portion and the second sub line portion overlap one another, and the first sub line portion and the second main line portion overlap one another.