An electronic device including a case, a covering plate, at least one first fixing unit, at least one second fixing unit, a circuit board disposed in the case, and a plurality of screwing members is provided. The case covered by the covering plate has a first datum surface and a second datum surface, where a distance between the covering plate and the first datum surface is greater than a distance between the covering plate and the second datum surface. The first and the second fixing units are disposed on the first and the second datum surfaces respectively. The first fixing unit includes a first screwing boss and at least one first rib adjacent thereto. The second fixing unit includes a second screwing boss and at least one second rib adjacent thereto. The screwing members pass through the covering plate and are screwed to the corresponding first and second screwing bosses.