An electronic device for an aircraft includes: a casing; a first boss projecting from a bottom wall of the casing toward an opening of the casing; a second boss projecting from the bottom wall of the casing toward the opening of the casing by a larger amount than the first boss; a first circuit board fixed to the first boss; and a second circuit board fixed to the second boss. The first circuit board includes cutouts penetrated by the second boss when the first circuit board is fixed to the first boss.