Abstract: A fastening device for a portable electrical device includes a base defining a curved sliding slot; a locking member rotatably attached to the base and a portion of the locking member capable of inserting into the portable electrical device and withdrawing from the portable electrical device; an actuating member rotatably attached to the base, and an elastical member fixed on the actuating member and the base, and capable of positioning the actuating member at a first position and a second position. The actuating member comprises a sliding portion and a driving portion. The sliding portion is movably received in the curved sliding slot, the driving portion contacting with the locking member.