An electronic device includes a first circuit board and a second circuit board arranged to have their first main surfaces facing each other, and a casing containing the first and second circuit boards. The first circuit board has the first main surface having a first electronic component with a mounting height from the first main surface toward the second circuit board greater than a distance between the first and second circuit boards. The second circuit board has an opening or a cutout as a first hollow portion facing the first electronic component. The first hollow portion receives a part of the first electronic component.