A flight device includes a device body with a surface, a plurality of arm structures disposed in the device body and a plurality of rotor modules disposed to the arm structures respectively. Each arm structure includes a fixing base, a second screw element, a connecting unit, a rod body and a position-limiting element. The fixing base is disposed in the device body and includes a first screw element having a first screw part. The second screw element has a second screw part matched with the first screw part. The connecting unit drills through the second screw element. The connecting unit is locked to the fixing base by screwing the first and second screw parts with each other. The rod body drills through the connecting unit. The position-limiting element is disposed between the second screw element and the connecting unit. The position-limiting element abuts against the second screw element.