a fastening device includes a cover , an actuating member rotatably attached on the cover , and a locking member disposed on the cover and engaging with the actuating member . the cover includes a hook capable of being locked and unlocked on an electronic device , and defines a through hole near the hook and the actuating member capable of rotating around a rotating center . the actuating member is locked on the cover while being pushed . the locking member including a locking portion capable of passing through the through hole and inserting into the electronic device to lock the hook on the electronic device and withdrawing from the through hole when the actuating member is pushed to rotate .